WorldWideScience

Sample records for atom probe characterization

  1. Atom probe field ion microscopy characterizations of VVER steels

    International Nuclear Information System (INIS)

    An atom probe field ion microscopy (APFIM) characterization of Soviet types 15Kh2MFA Cr-Mo-V (VVER 440) and 15Kh2NMFA Ni-Cr-Mo-V (VVER 1000) pressure vessel steels has been performed. Field ion microscopy has revealed that the lath boundaries in unirradiated VVER 440 and VVER 1000 steels are decorated with a thin film of brightly-imaging molybdenum carbonitride precipitates and some coarser vanadium carbides. Atom probe analysis has revealed significant enrichments of phosphorous at the lath boundaries

  2. Conductive-probe atomic force microscopy characterization of silicon nanowire

    Directory of Open Access Journals (Sweden)

    Yu Linwei

    2011-01-01

    Full Text Available Abstract The electrical conduction properties of lateral and vertical silicon nanowires (SiNWs were investigated using a conductive-probe atomic force microscopy (AFM. Horizontal SiNWs, which were synthesized by the in-plane solid-liquid-solid technique, are randomly deployed into an undoped hydrogenated amorphous silicon layer. Local current mapping shows that the wires have internal microstructures. The local current-voltage measurements on these horizontal wires reveal a power law behavior indicating several transport regimes based on space-charge limited conduction which can be assisted by traps in the high-bias regime (> 1 V. Vertical phosphorus-doped SiNWs were grown by chemical vapor deposition using a gold catalyst-driving vapor-liquid-solid process on higly n-type silicon substrates. The effect of phosphorus doping on the local contact resistance between the AFM tip and the SiNW was put in evidence, and the SiNWs resistivity was estimated.

  3. Quantitative atom probe tomography characterization of microstructures in a proton irradiated 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yimeng [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States); Chou, Peter H. [Electric Power Research Institute, Palo Alto, CA 94304 (United States); Marquis, Emmanuelle A., E-mail: emarq@umich.edu [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2014-08-01

    Abstract: Irradiation of 304 stainless steels induces complex microstructural changes such as solute clustering, precipitation, and segregation to dislocations, which have been best characterized by atom probe tomography. However, reliably and reproducibly quantifying these localized chemical changes can be challenging. To this end, an approach for quantitative cluster and dislocation analysis of the atom probe tomography data is proposed. The method is applied to the quantification of Cu clusters, Ni–Si rich clusters and Si, Ni and P segregation to dislocations that are observed in a 304 stainless steel that was proton irradiated at 360 °C to 10 dpa.

  4. THE ORNL ATOM PROBE

    OpenAIRE

    Miller, M

    1986-01-01

    The ORNL Atom Probe is a microanalytical tool for studies in materials science. The instrument is a combination of a customized version of the vacuum system of the VG FIM-100 atom probe, an ORNL-designed microcomputer-controlled digital timing system, and a double curved CEMA Imaging Atom Probe detector. The atom probe combines four instruments into one - namely a field ion microscope, an energy compensated time-of-flight mass spectrometer, an imaging atom probe, and a pulsed laser atom probe.

  5. Atom probe tomography today

    Directory of Open Access Journals (Sweden)

    Alfred Cerezo

    2007-12-01

    Full Text Available This review aims to describe and illustrate the advances in the application of atom probe tomography that have been made possible by recent developments, particularly in specimen preparation techniques (using dual-beam focused-ion beam instruments but also of the more routine use of laser pulsing. The combination of these two developments now permits atomic-scale investigation of site-specific regions within engineering alloys (e.g. at grain boundaries and in the vicinity of cracks and also the atomic-level characterization of interfaces in multilayers, oxide films, and semiconductor materials and devices.

  6. Characterization of designed cobaltacarborane porphyrins using conductive probe atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Venetia D. Lyles

    2016-03-01

    Full Text Available Porphyrins and metalloporphyrins have unique chemical and electronic properties and thus provide useful model structures for studies of nanoscale electronic properties. The rigid planar structures and -conjugated backbones of porphyrins convey robust electrical characteristics. For our investigations, cobaltacarborane porphyrins were synthesized using a ring-opening zwitterionic reaction to produce isomers with selected arrangements of carborane clusters on each macrocycle. Experiments were designed to investigate how the molecular structure influences the self-organization, surface assembly, and conductive properties of three molecular structures with 2, 4, or 8 cobaltacarborane substituents. Current versus voltage (I-V spectra for designed cobaltacarborane porphyrins deposited on conductive gold substrates were acquired using conductive probe atomic force microscopy (CP-AFM. Characterizations with CP-AFM provide capabilities for obtaining physical measurements and structural information with unprecedented sensitivity. We found that the morphology of cobaltacarborane porphyrin structures formed on surfaces depends on a complex interplay of factors such as the solvent used for dissolution, the nature of the substrate, and the design of the parent molecule. The conductive properties of cobaltacarborane porphyrins were observed to change according to the arrangement of cobaltacarborane substituents. Specifically, the number and placement of the cobaltacarborane ligands on the porphyrin macrocycle affect the interactions that drive porphyrin self-assembly and crystallization. Interestingly, coulombic staircase I-V profiles were detected for a porphyrin with two cobaltacarborane substituents.

  7. Characterization of microfabricated probes for combined atomic force and high-resolution scanning electrochemical microscopy.

    Science.gov (United States)

    Gullo, Maurizio R; Frederix, Patrick L T M; Akiyama, Terunobu; Engel, Andreas; deRooij, Nico F; Staufer, Urs

    2006-08-01

    A combined atomic force and scanning electrochemical microscope probe is presented. The probe is electrically insulated except at the very apex of the tip, which has a radius of curvature in the range of 10-15 nm. Steady-state cyclic voltammetry measurements for the reduction of Ru(NH3)6Cl3 and feedback experiments showed a distinct and reproducible response of the electrode. These experimental results agreed with finite element simulations for the corresponding diffusion process. Sequentially topographical and electrochemical studies of Pt lines deposited onto Si3N4 and spaced 100 nm apart (edge to edge) showed a lateral electrochemical resolution of 10 nm. PMID:16878880

  8. Atom Probe Tomography 2012

    Science.gov (United States)

    Kelly, Thomas F.; Larson, David J.

    2012-08-01

    In the world of tomographic imaging, atom probe tomography (APT) occupies the high-spatial-resolution end of the spectrum. It is highly complementary to electron tomography and is applicable to a wide range of materials. The current state of APT is reviewed. Emphasis is placed on applications and data analysis as they apply to many fields of research and development including metals, semiconductors, ceramics, and organic materials. We also provide a brief review of the history and the instrumentation associated with APT and an assessment of the existing challenges in the field.

  9. Characterization of nano-sized precipitates in a Mn-based lean maraging steel by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Millan, J.; Ponge, D.; Raabe, D.; Choi, P.; Dmitrieva, O. [Max-Planck-Institut fuer Eisenforschung, Duesseldorf (Germany)

    2011-02-15

    We present atom probe tomography results of a precipitation-hardened Mn-based maraging steel (9 Mn, 1.9 Ni, 0.6 Mo, 1.1 Ti, 0.33 Al; in at.%). The alloy is characterized by the surprising effect that both, strength and total elongation increase upon aging. The material reveals a high ultimate tensile strength (UTS) up to 1 GPa and good ductility (total elongation (TE) of up to 15% in a tensile test) depending on aging conditions. We map the evolution of the precipitates after 450 C aging treatment using atom probe tomography in terms of chemical composition and size distribution. (Copyright copyright 2011 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    International Nuclear Information System (INIS)

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs). The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impack 41-J shifts and the corresponding fluences are 192 deg C at 5.0 x 1023 n/m2 (>1 MeV) for Unit 3 and 162 deg C at 6.0 x 1023 n/m2 (1 MeV) for unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel-manganese-silicon phases. Atom probe tomography measurements have revealed ∼2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese-nickel-silicon-enriched precipitates rather than changes in their size or number density.

  11. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    International Nuclear Information System (INIS)

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs) designed and supplied by Westinghouse Electric Company, with commercial operation in 1981 and 1983, respectively. The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impact 41-J shifts and corresponding fluences are 192 °C at 5.0 × 1023 n/m2 (>1 MeV) for Unit 3 and 162 °C at 6.0 × 1023 n/m2 (>1 MeV) for Unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel–manganese–silicon phases. Atom probe tomography measurements have revealed ∼2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese–nickel–silicon-enriched precipitates rather than changes in their size or number density

  12. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    Science.gov (United States)

    Miller, M. K.; Powers, K. A.; Nanstad, R. K.; Efsing, P.

    2013-06-01

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs) designed and supplied by Westinghouse Electric Company, with commercial operation in 1981 and 1983, respectively. The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impact 41-J shifts and corresponding fluences are 192 °C at 5.0 × 1023 n/m2 (>1 MeV) for Unit 3 and 162 °C at 6.0 × 1023 n/m2 (>1 MeV) for Unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel-manganese-silicon phases. Atom probe tomography measurements have revealed ˜2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese-nickel-silicon-enriched precipitates rather than changes in their size or number density.

  13. Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy

    OpenAIRE

    Muna Khushaim; Torben Boll; Judith Seibert; Ferdinand Haider; Talaat Al-Kassab

    2015-01-01

    The microstructure of the commercial alloy AA2195 was investigated on the nano-scale after conducting a T8 tempering. This particular thermo-mechanical treatment of the specimen resulted in the formation of platelet-shaped $T_{1}$ ($Al_{2}CuLi$)/ $\\theta^{'}$($Al_{2}Cu$) within the Al-matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. The $\\theta^{'}$ platelets, which are less than 2 nm thic...

  14. Influence of the Electronic Structure and Optical Properties of CeO2 and UO2 for Characterization with UV-Laser Assisted Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Billy Valderrama; H.B. Henderson; C. Yablinsky; J. Gan; T.R. Allen; M.V. Manuel

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  15. Characterization of duplex stainless steels by TEM [transmission electron microscopy], SANS [small-angle neutron scattering], and APFIM [atom-probe field ion microscopy] techniques

    International Nuclear Information System (INIS)

    Results are presented of complementary characterization of aged duplex stainless steels by advanced metallographic techniques, including transmission and high-voltage electron microscopies; small-angle neutron scattering; and atom-probe field ion microscopy. On the basis of the characterization, the mechanisms of aging embrittlement have been shown to be associated with the precipitation of Ni- and Si-rich G phase and Cr-rich α' in the ferrite, and M23C6 carbides on the austenite-ferrite phase boundaries. 19 refs., 19 figs., 1 tab

  16. Atom Probe Tomography Characterization of the Solute Distributions in a Neutron-Irradiated and Annealed Pressure Vessel Steel Weld

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.K.

    2001-01-30

    A combined atom probe tomography and atom probe field ion microscopy study has been performed on a submerged arc weld irradiated to high fluence in the Heavy-Section Steel irradiation (HSSI) fifth irradiation series (Weld 73W). The composition of this weld is Fe - 0.27 at. % Cu, 1.58% Mn, 0.57% Ni, 0.34% MO, 0.27% Cr, 0.58% Si, 0.003% V, 0.45% C, 0.009% P, and 0.009% S. The material was examined after five conditions: after a typical stress relief treatment of 40 h at 607 C, after neutron irradiation to a fluence of 2 x 10{sup 23} n m{sup {minus}2} (E > 1 MeV), and after irradiation and isothermal anneals of 0.5, 1, and 168 h at 454 C. This report describes the matrix composition and the size, composition, and number density of the ultrafine copper-enriched precipitates that formed under neutron irradiation and the change in these parameters with post-irradiation annealing treatments.

  17. Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Muna Khushaim

    2015-01-01

    Full Text Available The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shaped T1Al2CuLi/θ′Al2Cu precipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. The θ′ platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al2Cu equilibrium composition. Additionally, the Li distribution inside the θ′ platelets was found to equal the same value as in the matrix. The equally thin T1 platelet deviates from the formula (Al2CuLi in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al2CuLi stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside the T1 platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thin T1 platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase.

  18. Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy

    KAUST Repository

    Khushaim, Muna

    2015-05-19

    The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shaped T 1 Al 2 CuLi / θ ′ Al 2 Cu precipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. The θ ′ platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al 2 Cu equilibrium composition. Additionally, the Li distribution inside the θ ′ platelets was found to equal the same value as in the matrix. The equally thin T 1 platelet deviates from the formula (Al 2 CuLi) in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al 2 CuLi) stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside the T 1 platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thin T 1 platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase.

  19. The future of atom probe tomography

    Directory of Open Access Journals (Sweden)

    Michael K. Miller

    2012-04-01

    Full Text Available The dream of the microscopy and materials science communities is to see, identify, accurately locate, and determine the fundamental physical properties of every atom in a specimen. With this knowledge together with modern computer models and simulations, a full understanding of the properties of a material can be determined. This fundamental knowledge leads to the design and development of more advanced materials for solving the needs of society. The technique of atom probe tomography is the closest to fulfilling this dream but is still significantly short of the goal. The future of atom probe tomography, and the prospects for achieving this ultimate goal are outlined.

  20. Characterization of the microstructure of dual-phase 9Cr-ODS steels using a laser-assisted 3D atom probe

    International Nuclear Information System (INIS)

    Dual-phase 9Cr-ODS (oxide dispersion-strengthened) steel consisting of residual-α ferrite and α' martensite has excellent high-temperature strength. This study describes the microstructure of dual-phase 9Cr-ODS steels characterized by atom-probe tomography in order to compare oxide-particle dispersion states in each phase. This revealed that nano-size oxide particles were of the same chemical composition and that their mean size was about 3 nm in each phase. On the other hand, the number density in the residual-α phase was about four times higher than that of the α' phase. These results indicate that the dense distribution of the oxide particles in the residual-α phase contribute to the excellent high-temperature strength of 9Cr-ODS steel.

  1. Pragmatic reconstruction methods in atom probe tomography

    International Nuclear Information System (INIS)

    Data collected in atom probe tomography have to be carefully analysed in order to give reliable composition data accurately and precisely positioned in the probed volume. Indeed, the large analysed surfaces of recent instruments require reconstruction methods taking into account not only the tip geometry but also accurate knowledge of geometrical projection parameters. This is particularly crucial in the analysis of multilayers materials or planar interfaces. The current work presents a simulation model that enables extraction of the two main projection features as a function of the tip and atom probe instrumentation geometries. Conversely to standard assumptions, the image compression factor and the field factor vary significantly during the analysis. An improved reconstruction method taking into account the intrinsic shape of a sample containing planar features is proposed to overcome this shortcoming. -- Highlights: → Tomographic reconstructions in atom probe tomography. → Model of field evaporation in a 2D non-regular geometry with cylindrical symmetry. → Calculation of the field factor and of the image compression factor. → New algorithm of reconstruction for specimen composed of flat layer structures.

  2. Comparative and complementary characterization of precipitate microstructures in Al-Mg-Si(-Li) alloys by transmission electron microscopy, energy dispersive X-ray spectroscopy and atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Koshino, Yuki [Department of Mechanical Engineering and Materials Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Kozuka, Masaya [Materials Research Laboratory, Kobe Steel, Ltd., 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-2271 (Japan); Hirosawa, Shoichi, E-mail: hirosawa@ynu.ac.jp [Department of Mechanical Engineering and Materials Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Aruga, Yasuhiro [Materials Research Laboratory, Kobe Steel, Ltd., 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-2271 (Japan)

    2015-02-15

    Highlights: • Microalloying addition of Li enhances the age-hardening response of Al-Mg-Si alloys. • Size and number density of nanoclusters or precipitates are increased by Li addition. • Mg and Si contents within the aggregates are inversely decreased by Li addition. • Microalloying Li accelerates heterogeneous nucleation of such Mg-Si aggregates. - Abstract: In this study, comparative and complementary characterization of precipitate microstructures by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and atom probe tomography (APT) has been performed for Al-0.55 wt%Mg-0.89 wt%Si(-0.043 wt%Li) alloys aged at 433 K for 1.2 ks (under aging) and 36 ks (peak aging). Quantitative estimation of nanometer-scale clusters (nanoclusters) and β″ precipitates by TEM and APT revealed that microalloying addition of Li increases the size and number density of these Mg-Si aggregates, resulting in the enhanced age-hardening response. Positive evidence by APT for the segregation of Li suggests that heterogeneous nucleation of such Mg-Si aggregates with the aid of Li is attributed to the modified precipitate microstructures and thus improved mechanical strength of this alloy system.

  3. Atom Probe Tomography of Nanoscale Electronic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Larson, David J.; Prosa, Ty J.; Perea, Daniel E.; Inoue, Hidekazu; Mangelinck, D.

    2016-01-01

    Atom probe tomography (APT) is a mass spectrometry based on time-of-flight measurements which also concurrently produces 3D spatial information. The reader is referred to any of the other papers in this volume or to the following references for further information 4–8. The current capabilities of APT, such as detecting a low number of dopant atoms in nanoscale devices or segregation at a nanoparticle interface, make this technique an important component in the nanoscale metrology toolbox. In this manuscript, we review some of the applications of APT to nanoscale electronic materials, including transistors and finFETs, silicide contact microstructures, nanowires, and nanoparticles.

  4. Mining information from atom probe data.

    Science.gov (United States)

    Cairney, Julie M; Rajan, Krishna; Haley, Daniel; Gault, Baptiste; Bagot, Paul A J; Choi, Pyuck-Pa; Felfer, Peter J; Ringer, Simon P; Marceau, Ross K W; Moody, Michael P

    2015-12-01

    Whilst atom probe tomography (APT) is a powerful technique with the capacity to gather information containing hundreds of millions of atoms from a single specimen, the ability to effectively use this information creates significant challenges. The main technological bottleneck lies in handling the extremely large amounts of data on spatial-chemical correlations, as well as developing new quantitative computational foundations for image reconstruction that target critical and transformative problems in materials science. The power to explore materials at the atomic scale with the extraordinary level of sensitivity of detection offered by atom probe tomography has not been not fully harnessed due to the challenges of dealing with missing, sparse and often noisy data. Hence there is a profound need to couple the analytical tools to deal with the data challenges with the experimental issues associated with this instrument. In this paper we provide a summary of some key issues associated with the challenges, and solutions to extract or "mine" fundamental materials science information from that data.

  5. Atom probe trajectory mapping using experimental tip shape measurements.

    Science.gov (United States)

    Haley, D; Petersen, T; Ringer, S P; Smith, G D W

    2011-11-01

    Atom probe tomography is an accurate analytical and imaging technique which can reconstruct the complex structure and composition of a specimen in three dimensions. Despite providing locally high spatial resolution, atom probe tomography suffers from global distortions due to a complex projection function between the specimen and detector which is different for each experiment and can change during a single run. To aid characterization of this projection function, this work demonstrates a method for the reverse projection of ions from an arbitrary projection surface in 3D space back to an atom probe tomography specimen surface. Experimental data from transmission electron microscopy tilt tomography are combined with point cloud surface reconstruction algorithms and finite element modelling to generate a mapping back to the original tip surface in a physically and experimentally motivated manner. As a case study, aluminium tips are imaged using transmission electron microscopy before and after atom probe tomography, and the specimen profiles used as input in surface reconstruction methods. This reconstruction method is a general procedure that can be used to generate mappings between a selected surface and a known tip shape using numerical solutions to the electrostatic equation, with quantitative solutions to the projection problem readily achievable in tens of minutes on a contemporary workstation. PMID:22004277

  6. Spatial resolution in atom probe tomography

    CERN Document Server

    Gault, Baptiste; de Geuser, Frederic; La Fontaine, Alex; Stephenson, Leigh T; Haley, Daniel; Ringer, Simon P

    2015-01-01

    This article addresses gaps in definitions and a lack of standard measurement techniques to assess the spatial resolution in atom probe tomography. This resolution is known to be anisotropic, being better in the depth than laterally. Generally the presence of atomic planes in the tomographic reconstruction is considered as being a sufficient proof of the quality of the spatial resolution of the instrument. Based on advanced spatial distribution maps, an analysis methodology that interrogates the local neighborhood of the atoms within the tomographic reconstruction, it is shown how both the in-depth and the lateral resolution can be quantified. The influences of the crystallography and the temperature are investigated, and models are proposed to explain the observed results. We demonstrate that the absolute value of resolution is specimenspecific.

  7. Preparation of Regular Specimens for Atom Probes

    Science.gov (United States)

    Kuhlman, Kim; Wishard, James

    2003-01-01

    A method of preparation of specimens of non-electropolishable materials for analysis by atom probes is being developed as a superior alternative to a prior method. In comparison with the prior method, the present method involves less processing time. Also, whereas the prior method yields irregularly shaped and sized specimens, the present developmental method offers the potential to prepare specimens of regular shape and size. The prior method is called the method of sharp shards because it involves crushing the material of interest and selecting microscopic sharp shards of the material for use as specimens. Each selected shard is oriented with its sharp tip facing away from the tip of a stainless-steel pin and is glued to the tip of the pin by use of silver epoxy. Then the shard is milled by use of a focused ion beam (FIB) to make the shard very thin (relative to its length) and to make its tip sharp enough for atom-probe analysis. The method of sharp shards is extremely time-consuming because the selection of shards must be performed with the help of a microscope, the shards must be positioned on the pins by use of micromanipulators, and the irregularity of size and shape necessitates many hours of FIB milling to sharpen each shard. In the present method, a flat slab of the material of interest (e.g., a polished sample of rock or a coated semiconductor wafer) is mounted in the sample holder of a dicing saw of the type conventionally used to cut individual integrated circuits out of the wafers on which they are fabricated in batches. A saw blade appropriate to the material of interest is selected. The depth of cut and the distance between successive parallel cuts is made such that what is left after the cuts is a series of thin, parallel ridges on a solid base. Then the workpiece is rotated 90 and the pattern of cuts is repeated, leaving behind a square array of square posts on the solid base. The posts can be made regular, long, and thin, as required for samples

  8. Contact resonances of U-shaped atomic force microscope probes

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, E.; Turner, J. A., E-mail: jaturner@unl.edu [Mechanical and Materials Engineering, University of Nebraska-Lincoln, W342 Nebraska Hall, Lincoln, Nebraska 68588 (United States)

    2016-01-21

    Recent approaches used to characterize the elastic or viscoelastic properties of materials with nanoscale resolution have focused on the contact resonances of atomic force microscope (CR-AFM) probes. The experiments for these CR-AFM methods involve measurement of several contact resonances from which the resonant frequency and peak width are found. The contact resonance values are then compared with the noncontact values in order for the sample properties to be evaluated. The data analysis requires vibration models associated with the probe during contact in order for the beam response to be deconvolved from the measured spectra. To date, the majority of CR-AFM research has used rectangular probes that have a relatively simple vibration response. Recently, U-shaped AFM probes have created much interest because they allow local sample heating. However, the vibration response of these probes is much more complex such that CR-AFM is still in its infancy. In this article, a simplified analytical model of U-shaped probes is evaluated for contact resonance applications relative to a more complex finite element (FE) computational model. The tip-sample contact is modeled using three orthogonal Kelvin-Voigt elements such that the resonant frequency and peak width of each mode are functions of the contact conditions. For the purely elastic case, the frequency results of the simple model are within 8% of the FE model for the lowest six modes over a wide range of contact stiffness values. Results for the viscoelastic contact problem for which the quality factor of the lowest six modes is compared show agreement to within 13%. These results suggest that this simple model can be used effectively to evaluate CR-AFM experimental results during AFM scanning such that quantitative mapping of viscoelastic properties may be possible using U-shaped probes.

  9. Contact resonances of U-shaped atomic force microscope probes

    International Nuclear Information System (INIS)

    Recent approaches used to characterize the elastic or viscoelastic properties of materials with nanoscale resolution have focused on the contact resonances of atomic force microscope (CR-AFM) probes. The experiments for these CR-AFM methods involve measurement of several contact resonances from which the resonant frequency and peak width are found. The contact resonance values are then compared with the noncontact values in order for the sample properties to be evaluated. The data analysis requires vibration models associated with the probe during contact in order for the beam response to be deconvolved from the measured spectra. To date, the majority of CR-AFM research has used rectangular probes that have a relatively simple vibration response. Recently, U-shaped AFM probes have created much interest because they allow local sample heating. However, the vibration response of these probes is much more complex such that CR-AFM is still in its infancy. In this article, a simplified analytical model of U-shaped probes is evaluated for contact resonance applications relative to a more complex finite element (FE) computational model. The tip-sample contact is modeled using three orthogonal Kelvin-Voigt elements such that the resonant frequency and peak width of each mode are functions of the contact conditions. For the purely elastic case, the frequency results of the simple model are within 8% of the FE model for the lowest six modes over a wide range of contact stiffness values. Results for the viscoelastic contact problem for which the quality factor of the lowest six modes is compared show agreement to within 13%. These results suggest that this simple model can be used effectively to evaluate CR-AFM experimental results during AFM scanning such that quantitative mapping of viscoelastic properties may be possible using U-shaped probes

  10. Soft-landing deposition of radioactive probe atoms on surfaces

    NARCIS (Netherlands)

    Laurens, C.R; Rosu, M.F; Pleiter, F; Niesen, L

    1999-01-01

    We present a method to deposit a wide range of radioactive probe atoms on surfaces, without introducing lattice damage or contaminating the surface with other elements or isotopes. In this method, the probe atoms are mass-separated using an isotope separa-tor, decelerated to 5 eV, and directly depos

  11. HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

    Science.gov (United States)

    Lefebvre, W; Hernandez-Maldonado, D; Moyon, F; Cuvilly, F; Vaudolon, C; Shinde, D; Vurpillot, F

    2015-12-01

    The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography.

  12. Manipulating collective quantum states of ultracold atoms by probing

    DEFF Research Database (Denmark)

    Wade, Andrew Christopher James

    2015-01-01

    nature of the measurement interaction and backaction is yet to be realised. This dissertation is concerned with ultracold atoms and their control via fully quantum mechanical probes. Nonclassical, squeezed and entangled states of matter and single photon sources are important for fundamental studies...... and quantum technologies. By probing, the production of squeezed and entangled states of collective variables in a Bose-Einstein condensate is investigated. Thereafter, an atomic probe using the strong interactions between highly excited atomic states, manipulates the light-matter dynamics of an ultracold gas...

  13. Depletion interaction measured by colloidal probe atomic force microscopy

    NARCIS (Netherlands)

    Wijting, W.K.; Knoben, W.; Besseling, N.A.M.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2004-01-01

    We investigated the depletion interaction between stearylated silica surfaces in cyclohexane in the presence of dissolved polydimethylsiloxane by means of colloidal probe atomic force microscopy. We found that the range of the depletion interaction decreases with increasing concentration. Furthermor

  14. Atomic probes of surface structure and dynamics

    International Nuclear Information System (INIS)

    Progress for the period Sept. 15, 1992 to Sept. 14, 1993 is discussed. Semiclassical methods that will allow much faster and more accurate three-dimensional atom--surface scattering calculations, both elastic and inelastic, are being developed. The scattering of He atoms from buckyballs is being investigated as a test problem. Somewhat more detail is given on studies of He atom scattering from defective Pt surfaces. Molecular dynamics simulations of He+ and Ar+ ion sputtering of Pt surfaces are also being done. He atom scattering from Xe overlayers on metal surfaces and the thermalized dissociation of H2 on Cu(110) are being studied. (R.W.R.) 64 refs

  15. Fabrication of an all-metal atomic force microscope probe

    DEFF Research Database (Denmark)

    Rasmussen, Jan Pihl; Tang, Peter Torben; Hansen, Ole;

    1997-01-01

    This paper presents a method for fabrication of an all-metal atomic force microscope probe (tip, cantilever and support) for optical read-out, using a combination of silicon micro-machining and electroforming. The paper describes the entire fabrication process for a nickel AFM-probe. In addition...

  16. Atom probe tomography of a commercial light emitting diode

    International Nuclear Information System (INIS)

    The atomic-scale analysis of a commercial light emitting diode device purchased at retail is demonstrated using a local electrode atom probe. Some of the features are correlated with transmission electron microscopy imaging. Subtle details of the structure that are revealed have potential significance for the design and performance of this device

  17. Probing a Bose-Einstein Condensate with an Atom Laser

    OpenAIRE

    Döring, D.; Robins, N. P.; Figl, C.; Close, J. D.

    2008-01-01

    A pulsed atom laser derived from a Bose-Einstein condensate is used to probe a second target condensate. The target condensate scatters the incident atom laser pulse. From the spatial distribution of scattered atoms, one can infer important properties of the target condensate and its interaction with the probe pulse. As an example, we measure the s-wave scattering length that, in low energy collisions, describes the interaction between the |F=1,m_F=-1> and |F=2,m_F=0> hyperfine ground states ...

  18. Probing Dark Energy with Atom Interferometry

    CERN Document Server

    Burrage, Clare; Hinds, E A

    2015-01-01

    Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry.

  19. Atom probe tomography of lithium-doped network glasses

    Energy Technology Data Exchange (ETDEWEB)

    Greiwe, Gerd-Hendrik, E-mail: g_grei01@uni-muenster.de [Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster (Germany); Balogh, Zoltan; Schmitz, Guido [Institute of Material Science, University of Stuttgart, Heisenberg Straße 3, D-70569 Stuttgart (Germany)

    2014-06-01

    Li-doped silicate and borate glasses are electronically insulating, but provide considerable ionic conductivity. Under measurement conditions of laser-assisted atom probe tomography, mobile Li ions are redistributed in response to high electric fields. In consequence, the direct interpretation of measured composition profiles is prevented. It is demonstrated that composition profiles are nevertheless well understood by a complex model taking into account the electronic structure of dielectric materials, ionic mobility and field screening. Quantitative data on band bending and field penetration during measurement are derived which are important in understanding laser-assisted atom probe tomography of dielectric materials. - Highlights: • Atom probe tomography is performed on ion conducting glasses. • Redistribution of ions during the measurement is observed. • An electrostatic model is applied to describe the electric field and ion diffusion. • Measurement is conducted of the absolute temperature during laser pulses.

  20. ATOM PROBE STUDY OF TITANIUM BASE ALLOYS : PRELIMINARY RESULTS

    OpenAIRE

    Menand, A.; Chambreland, S.; Martin, C

    1986-01-01

    Two different titanium base alloys, Ti46 Al54 and Ti88.8 Cu2.3, Al8.9, have been studied by atom probe microanalysis. A precipitate of Ti2 Al was analysed in the binary alloys. Micro-analysis of Ti Cu Al alloy revealed the presence of Copper enriched zones. The study has also exhibited a penetration of Hydrogen in the samples, probably due to preparation technique. The results demonstrate the feasibility of studies on titanium base alloys by mean of atom probe.

  1. Encapsulation method for atom probe tomography analysis of nanoparticles

    NARCIS (Netherlands)

    Larson, D.J.; Giddings, A.D.; Wub, Y.; Verheijen, M.A.; Prosa, T.J.; Roozeboom, F.; Rice, K.P.; Kessels, W.M.M.; Geiser, B.P.; Kelly, T.F.

    2015-01-01

    Open-space nanomaterials are a widespread class of technologically important materials that are generally incompatible with analysis by atom probe tomography (APT) due to issues with specimen preparation, field evaporation and data reconstruction. The feasibility of encapsulating such non-compact ma

  2. Design of cantilever probes for Atomic Force Microscopy (AFM)

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2000-01-01

    A cantilever beam used in an Atomic Force Microscope is optimized with respect to two different objectives. The first goal is to maximize the first eigenfrequency while keeping the stiffness of the probe constant. The second goal is to maximize the tip angle of the first eigenmode while again...

  3. Data mining for isotope discrimination in atom probe tomography

    International Nuclear Information System (INIS)

    Ions with similar time-of-flights (TOF) can be discriminated by mapping their kinetic energy. While current generation position-sensitive detectors have been considered insufficient for capturing the isotope kinetic energy, we demonstrate in this paper that statistical learning methodologies can be used to capture the kinetic energy from all of the parameters currently measured by mathematically transforming the signal. This approach works because the kinetic energy is sufficiently described by the descriptors on the potential, the material, and the evaporation process within atom probe tomography (APT). We discriminate the isotopes for Mg and Al by capturing the kinetic energy, and then decompose the TOF spectrum into its isotope components and identify the isotope for each individual atom measured. This work demonstrates the value of advanced data mining methods to help enhance the information resolution of the atom probe. - Highlights: ► Atom probe tomography and statistical learning were combined for data enhancement. ► Multiple eigenvalue decompositions decomposed a spectrum with overlapping peaks. ► The isotope of each atom was determined by kinetic energy discrimination. ► Eigenspectra were identified and new chemical information was identified

  4. New Methods of Sample Preparation for Atom Probe Specimens

    Science.gov (United States)

    Kuhlman, Kimberly, R.; Kowalczyk, Robert S.; Ward, Jennifer R.; Wishard, James L.; Martens, Richard L.; Kelly, Thomas F.

    2003-01-01

    Magnetite is a common conductive mineral found on Earth and Mars. Disk-shaped precipitates approximately 40 nm in diameter have been shown to have manganese and aluminum concentrations. Atom-probe field-ion microscopy (APFIM) is the only technique that can potentially quantify the composition of these precipitates. APFIM will be used to characterize geological and planetary materials, analyze samples of interest for geomicrobiology; and, for the metrology of nanoscale instrumentation. Prior to APFIM sample preparation was conducted by electropolishing, the method of sharp shards (MSS), or Bosch process (deep reactive ion etching) with focused ion beam (FIB) milling as a final step. However, new methods are required for difficult samples. Many materials are not easily fabricated using electropolishing, MSS, or the Bosch process, FIB milling is slow and expensive, and wet chemistry and the reactive ion etching are typically limited to Si and other semiconductors. APFIM sample preparation using the dicing saw is commonly used to section semiconductor wafers into individual devices following manufacture. The dicing saw is a time-effective method for preparing high aspect ratio posts of poorly conducting materials. Femtosecond laser micromachining is also suitable for preparation of posts. FIB time required is reduced by about a factor of 10 and multi-tip specimens can easily be fabricated using the dicing saw.

  5. Distributed force probe bending model of critical dimension atomic force microscopy bias

    Science.gov (United States)

    Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.

    2013-04-01

    Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.

  6. New approaches to nanoparticle sample fabrication for atom probe tomography.

    Science.gov (United States)

    Felfer, P; Li, T; Eder, K; Galinski, H; Magyar, A P; Bell, D C; Smith, G D W; Kruse, N; Ringer, S P; Cairney, J M

    2015-12-01

    Due to their unique properties, nano-sized materials such as nanoparticles and nanowires are receiving considerable attention. However, little data is available about their chemical makeup at the atomic scale, especially in three dimensions (3D). Atom probe tomography is able to answer many important questions about these materials if the challenge of producing a suitable sample can be overcome. In order to achieve this, the nanomaterial needs to be positioned within the end of a tip and fixed there so the sample possesses sufficient structural integrity for analysis. Here we provide a detailed description of various techniques that have been used to position nanoparticles on substrates for atom probe analysis. In some of the approaches, this is combined with deposition techniques to incorporate the particles into a solid matrix, and focused ion beam processing is then used to fabricate atom probe samples from this composite. Using these approaches, data has been achieved from 10-20 nm core-shell nanoparticles that were extracted directly from suspension (i.e. with no chemical modification) with a resolution of better than ± 1 nm.

  7. Atom-probe investigations of TiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Menand, A.; Zapolsky-Tatarenko, H.; Nerac-Partaix, A. [Rouen Univ., Mont-Saint-Aignan (France). Fac. des Sci.

    1998-07-15

    Atom probe field ion microscopy (APFIM) and tomographic atom probe (TAP) have been used to study TiAl-based alloys. The element concentrations, the influence of additional elements such as Cr or Nb as well as the solubility of oxygen in {alpha}{sub 2} (Ti{sub 3}Al) and {gamma} (TiAl) phases in compounds with nominal concentration Ti{sub 54}Al{sub 46} and Ti{sub 58}Al{sub 42} have been determined. By using the detection of oxygen atoms as a very local probe, the present investigation revealed the existence of some intermediate phases during the phase transformation {alpha}{yields}{gamma}. The presence of the oxygen atoms during this transformation gives some peculiarities on the transformation path. The appearance of some metastable phases may be explained by the existence of the homologous series Ti{sub 2n-1}Al{sub n} where n is an integer varying from 1 (stoichiometry TiAl) to {infinity} (phase {alpha}{sub 3} Ti{sub 2}Al). (orig.) 35 refs.

  8. Visualization of deuterium dead layer by atom probe tomography

    KAUST Repository

    Gemma, Ryota

    2012-12-01

    The first direct observation, by atom probe tomography, of a deuterium dead layer is reported for Fe/V multilayered film loaded with D solute atoms. The thickness of the dead layers was measured to be 0.4-0.5 nm. The dead layers could be distinguished from chemically intermixed layers. The results suggest that the dead layer effect occurs even near the interface of the mixing layers, supporting an interpretation that the dead layer effect cannot be explained solely by electronic charge transfer but also involves a modulation of rigidity. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Probing stem cell differentiation using atomic force microscopy

    Science.gov (United States)

    Liang, Xiaobin; Shi, Xuetao; Ostrovidov, Serge; Wu, Hongkai; Nakajima, Ken

    2016-03-01

    A real-time method using atomic force microscopy (AFM) was developed to probe stem cell differentiation by measuring the mechanical properties of cells and the extracellular matrix (ECM). The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. It is clear that AFM is a facile and useful tool for monitoring the differentiation of stem cells in a non-invasive manner.

  10. Atom-probe tomography of tribological boundary films resulting from boron-based oil additives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoon-Jun; Baik, Sung-Il; Bertolucci-Coelho, Leonardo; Mazzaferro, Lucca; Ramirez, Giovanni; Erdemir, Ali; Seidman, D K

    2016-01-15

    Correlative characterization using atom-probe tomography (APT) and transmission electron microscopy (TEM) was performed on a tribofilm formed during sliding frictional testing with a fully formulated engine oil, which also contains a boron-based additive. The tribofilm formed is ~15 nm thick and consists of oxides of iron and compounds of B, Ca, P, and S, which are present in the additive. This study provides strong evidence for boron being embedded in the tribofilm, which effectively reduces friction and wear losses.

  11. New atom probe approaches to studying segregation in nanocrystalline materials

    International Nuclear Information System (INIS)

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess

  12. New atom probe approaches to studying segregation in nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Cao, Y.; Liao, X.Z. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); Cairney, J.M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

    2013-09-15

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess.

  13. Atom chip microscopy: A novel probe for strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Lev, Benjamin L

    2011-11-03

    Improved measurements of strongly correlated systems will enable the predicative design of the next generation of supermaterials. In this program, we are harnessing recent advances in the quantum manipulation of ultracold atomic gases to expand our ability to probe these technologically important materials in heretofore unexplored regions of temperature, resolution, and sensitivity parameter space. We are working to demonstrate the use of atom chips to enable single-shot, large area detection of magnetic flux at the 10^-7 flux quantum level and below. By harnessing the extreme sensitivity of atomic clocks and Bose-Einstein condensates (BECs) to external perturbations, the cryogenic atom chip technology developed here will provide a magnetic flux detection capability that surpasses other techniques---such as scanning SQUIDs---by a factor of 10--1000. We are testing the utility of this technique by using rubidium BECs to image the magnetic fields emanating from charge transport and magnetic domain percolation in strongly correlated materials as they undergo temperature-tuned metal--to--insulator phase transitions. Cryogenic atom chip microscopy introduces three very important features to the toolbox of high-resolution, strongly correlated material microscopy: simultaneous detection of magnetic and electric fields (down to the sub-single electron charge level); no invasive large magnetic fields or gradients; simultaneous micro- and macroscopic spatial resolution; freedom from 1/f flicker noise at low frequencies; and, perhaps most importantly, the complete decoupling of probe and sample temperatures. The first of these features will play an important role in studying the interplay between magnetic and electric domain structure. The last two are crucial for low frequency magnetic noise detection in, e.g., the cuprate pseudogap region and for precision measurements of transport in the high temperature, technologically relevant regime inaccessible to other techniques

  14. Multifunctional hydrogel nano-probes for atomic force microscopy

    Science.gov (United States)

    Lee, Jae Seol; Song, Jungki; Kim, Seong Oh; Kim, Seokbeom; Lee, Wooju; Jackman, Joshua A.; Kim, Dongchoul; Cho, Nam-Joon; Lee, Jungchul

    2016-05-01

    Since the invention of the atomic force microscope (AFM) three decades ago, there have been numerous advances in its measurement capabilities. Curiously, throughout these developments, the fundamental nature of the force-sensing probe--the key actuating element--has remained largely unchanged. It is produced by long-established microfabrication etching strategies and typically composed of silicon-based materials. Here, we report a new class of photopolymerizable hydrogel nano-probes that are produced by bottom-up fabrication with compressible replica moulding. The hydrogel probes demonstrate excellent capabilities for AFM imaging and force measurement applications while enabling programmable, multifunctional capabilities based on compositionally adjustable mechanical properties and facile encapsulation of various nanomaterials. Taken together, the simple, fast and affordable manufacturing route and multifunctional capabilities of hydrogel AFM nano-probes highlight the potential of soft matter mechanical transducers in nanotechnology applications. The fabrication scheme can also be readily utilized to prepare hydrogel cantilevers, including in parallel arrays, for nanomechanical sensor devices.

  15. Clustered field evaporation of metallic glasses in atom probe tomography.

    Science.gov (United States)

    Zemp, J; Gerstl, S S A; Löffler, J F; Schönfeld, B

    2016-03-01

    Field evaporation of metallic glasses is a stochastic process combined with spatially and temporally correlated events, which are referred to as clustered evaporation (CE). This phenomenon is investigated by studying the distance between consecutive detector hits. CE is found to be a strongly localized phenomenon (up to 3nm in range) which also depends on the type of evaporating ions. While a similar effect in crystals is attributed to the evaporation of crystalline layers, CE of metallic glasses presumably has a different - as yet unknown - physical origin. The present work provides new perspectives on quantification methods for atom probe tomography of metallic glasses.

  16. Reflections on the projection of ions in atom probe tomography

    CERN Document Server

    De Geuser, Frédéric

    2016-01-01

    There are two main projections used to transform, and reconstruct, field ion micrographs or atom probe tomography data into atomic coordinates at the specimen surface and, subsequently, in three-dimensions. In this article, we present a perspective on the strength of the azimuthal equidistant projection in comparison to the more widely used and well-established point-projection, which underpins data reconstruction in the only commercial software package available currently. After an overview of the reconstruction methodology, we demonstrate that the azimuthal equidistant is not only more accurate, but also more robust with regards to errors on the parameters used to perform the reconstruction and is therefore more likely to yield more accurate tomographic reconstructions.

  17. Towards an accurate volume reconstruction in atom probe tomography.

    Science.gov (United States)

    Beinke, Daniel; Oberdorfer, Christian; Schmitz, Guido

    2016-06-01

    An alternative concept for the reconstruction of atom probe data is outlined. It is based on the calculation of realistic trajectories of the evaporated ions in a recursive refinement process. To this end, the electrostatic problem is solved on a Delaunay tessellation. To enable the trajectory calculation, the order of reconstruction is inverted with respect to previous reconstruction schemes: the last atom detected is reconstructed first. In this way, the emitter shape, which controls the trajectory, can be defined throughout the duration of the reconstruction. A proof of concept is presented for 3D model tips, containing spherical precipitates or embedded layers of strongly contrasting evaporation thresholds. While the traditional method following Bas et al. generates serious distortions in these cases, a reconstruction with the proposed electrostatically informed approach improves the geometry of layers and particles significantly.

  18. Submolecular Imaging by Noncontact Atomic Force Microscopy with an Oxygen Atom Rigidly Connected to a Metallic Probe.

    Science.gov (United States)

    Mönig, Harry; Hermoso, Diego R; Díaz Arado, Oscar; Todorović, Milica; Timmer, Alexander; Schüer, Simon; Langewisch, Gernot; Pérez, Rubén; Fuchs, Harald

    2016-01-26

    In scanning probe microscopy, the imaging characteristics in the various interaction channels crucially depend on the chemical termination of the probe tip. Here we analyze the contrast signatures of an oxygen-terminated copper tip with a tetrahedral configuration of the covalently bound terminal O atom. Supported by first-principles calculations we show how this tip termination can be identified by contrast analysis in noncontact atomic force and scanning tunneling microscopy (NC-AFM, STM) on a partially oxidized Cu(110) surface. After controlled tip functionalization by soft indentations of only a few angstroms in an oxide nanodomain, we demonstrate that this tip allows imaging an organic molecule adsorbed on Cu(110) by constant-height NC-AFM in the repulsive force regime, revealing its internal bond structure. In established tip functionalization approaches where, for example, CO or Xe is deliberately picked up from a surface, these probe particles are only weakly bound to the metallic tip, leading to lateral deflections during scanning. Therefore, the contrast mechanism is subject to image distortions, artifacts, and related controversies. In contrast, our simulations for the O-terminated Cu tip show that lateral deflections of the terminating O atom are negligible. This allows a detailed discussion of the fundamental imaging mechanisms in high-resolution NC-AFM experiments. With its structural rigidity, its chemically passivated state, and a high electron density at the apex, we identify the main characteristics of the O-terminated Cu tip, making it a highly attractive complementary probe for the characterization of organic nanostructures on surfaces. PMID:26605698

  19. Materials applications of an advanced 3-dimensional atom probe

    Energy Technology Data Exchange (ETDEWEB)

    Cerezo, A. [Oxford Univ. (United Kingdom). Dept. of Materials; Gibuoin, D. [Oxford Univ. (United Kingdom). Dept. of Materials; Kim, S. [Oxford Univ. (United Kingdom). Dept. of Materials; Sijbrandij, S.J. [Oxford Univ. (United Kingdom). Dept. of Materials; Venker, F.M. [Oxford Univ. (United Kingdom). Dept. of Materials]|[Rijksuniversiteit Groningen (Netherlands). Dept. of Applied Physics; Warren, P.J. [Oxford Univ. (United Kingdom). Dept. of Materials; Wilde, J. [Oxford Univ. (United Kingdom). Dept. of Materials; Smith, G.D.W. [Oxford Univ. (United Kingdom). Dept. of Materials

    1996-09-01

    An advanced 3-dimensional atom probe system has been constructed, based on an optical position-sensitive atom probe (OPoSAP) detector with energy compensation using a reflectron lens. The multi-hit detection capability of the OPoSAP leads to significant improvements in the efficiency of the instrument over the earlier serial position-sensing system. Further gains in efficiency are obtained by using a biassed grid in front of the detector to collect secondary electrons generated when ions strike the interchannel area. The improvement in detection efficiency gives enhanced performance in the studies of ordered materials and the determination of site occupation. Energy compensation leads to a much improved mass resolution (m/{Delta}m=500 full width at half maximum) making it possible to map out the 3-dimensional spatial distributions of all the elements in complex engineering alloys, even when elements lie close together in the mass spectrum. For example, in the analysis of a maraging steel, this allows separation between the {sup 61}Ni{sup 2+} and {sup 92}Mo{sup 3+} peaks, which are only 1/6 of a mass unit apart. (orig.).

  20. Generating and probing entangled states for optical atomic clocks

    Science.gov (United States)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2016-05-01

    The precision of quantum measurements is inherently limited by projection noise caused by the measurement process itself. Spin squeezing and more complex forms of entanglement have been proposed as ways of surpassing this limitation. In our system, a high-finesse asymmetric micromirror-based optical cavity can mediate the atom-atom interaction necessary for generating entanglement in an 171 Yb optical lattice clock. I will discuss approaches for creating, characterizing, and optimally utilizing these nonclassical states for precision measurement, as well as recent progress toward their realization. This research is supported by DARPA QuASAR, NSF, and NSERC.

  1. Probing modified gravity with atom-interferometry: A numerical approach

    Science.gov (United States)

    Schlögel, Sandrine; Clesse, Sébastien; Füzfa, André

    2016-05-01

    Refined constraints on chameleon theories are calculated for atom-interferometry experiments, using a numerical approach consisting in solving for a four-region model the static and spherically symmetric Klein-Gordon equation for the chameleon field. By modeling not only the test mass and the vacuum chamber but also its walls and the exterior environment, the method allows one to probe new effects on the scalar field profile and the induced acceleration of atoms. In the case of a weakly perturbing test mass, the effect of the wall is to enhance the field profile and to lower the acceleration inside the chamber by up to 1 order of magnitude. In the thin-shell regime, results are found to be in good agreement with the analytical estimations, when measurements are realized in the immediate vicinity of the test mass. Close to the vacuum chamber wall, the acceleration becomes negative and potentially measurable. This prediction could be used to discriminate between fifth-force effects and systematic experimental uncertainties, by doing the experiment at several key positions inside the vacuum chamber. For the chameleon potential V (ϕ )=Λ4 +α/ϕα and a coupling function A (ϕ )=exp (ϕ /M ), one finds M ≳7 ×1016 GeV , independently of the power-law index. For V (ϕ )=Λ4(1 +Λ /ϕ ), one finds M ≳1014 GeV . A sensitivity of a ˜10-11 m /s2 would probe the model up to the Planck scale. Finally, a proposal for a second experimental setup, in a vacuum room, is presented. In this case, Planckian values of M could be probed provided that a ˜10-10 m /s2 , a limit reachable by future experiments. Our method can easily be extended to constrain other models with a screening mechanism, such as symmetron, dilaton and f(R) theories.

  2. Nondestructive characterization of municipal-solid-waste-contaminated surface soil by energy-dispersive X-ray fluorescence and low-Z (atomic number) particle electron probe X-ray microanalysis.

    Science.gov (United States)

    Gupta, Dhrubajyoti; Ghosh, Rita; Mitra, Ajoy K; Roy, Subinit; Sarkar, Manoranjan; Chowdhury, Subhajit; Bhowmik, Asit; Mukhopadhyay, Ujjal; Maskey, Shila; Ro, Chul-Un

    2011-11-01

    The long-term environmental impact of municipal solid waste (MSW) landfilling is still under investigation due to the lack of detailed characterization studies. A MSW landfill site, popularly known as Dhapa, in the eastern fringe of the metropolis of Kolkata, India, is the subject of present study. A vast area of Dhapa, adjoining the current core MSW dump site and evolving from the raw MSW dumping in the past, is presently used for the cultivation of vegetables. The inorganic chemical characteristics of the MSW-contaminated Dhapa surface soil (covering a 2-km stretch of the area) along with a natural composite (geogenic) soil sample (from a small countryside farm), for comparison, were investigated using two complementary nondestructive analytical techniques, energy-dispersive X-ray fluorescence (EDXRF) for bulk analysis and low-Z (atomic number) particle electron probe X-ray microanalysis (low-Z particle EPMA) for single-particle analysis. The bulk concentrations of K, Rb, and Zr remain almost unchanged in all the soil samples. The Dhapa soil is found to be polluted with heavy metals such as Cu, Zn, and Pb (highly elevated) and Ti, Cr, Mn, Fe, Ni, and Sr (moderately elevated), compared to the natural countryside soil. These high bulk concentration levels of heavy metals were compared with the Ecological Soil Screening Levels for these elements (U.S. Environment Protection Agency) to assess the potential risk on the immediate biotic environment. Low-Z particle EPMA results showed that the aluminosilicate-containing particles were the most abundant, followed by SiO2, CaCO3-containing, and carbonaceous particles in the Dhapa samples, whereas in the countryside sample only aluminosilicate-containing and SiO2 particles were observed. The mineral particles encountered in the countryside sample are solely of geogenic origin, whereas those from the Dhapa samples seem to have evolved from a mixture of raw dumped MSW, urban dust, and other contributing factors such as wind

  3. Nondestructive characterization of municipal-solid-waste-contaminated surface soil by energy-dispersive X-ray fluorescence and low-Z (atomic number) particle electron probe X-ray microanalysis.

    Science.gov (United States)

    Gupta, Dhrubajyoti; Ghosh, Rita; Mitra, Ajoy K; Roy, Subinit; Sarkar, Manoranjan; Chowdhury, Subhajit; Bhowmik, Asit; Mukhopadhyay, Ujjal; Maskey, Shila; Ro, Chul-Un

    2011-11-01

    The long-term environmental impact of municipal solid waste (MSW) landfilling is still under investigation due to the lack of detailed characterization studies. A MSW landfill site, popularly known as Dhapa, in the eastern fringe of the metropolis of Kolkata, India, is the subject of present study. A vast area of Dhapa, adjoining the current core MSW dump site and evolving from the raw MSW dumping in the past, is presently used for the cultivation of vegetables. The inorganic chemical characteristics of the MSW-contaminated Dhapa surface soil (covering a 2-km stretch of the area) along with a natural composite (geogenic) soil sample (from a small countryside farm), for comparison, were investigated using two complementary nondestructive analytical techniques, energy-dispersive X-ray fluorescence (EDXRF) for bulk analysis and low-Z (atomic number) particle electron probe X-ray microanalysis (low-Z particle EPMA) for single-particle analysis. The bulk concentrations of K, Rb, and Zr remain almost unchanged in all the soil samples. The Dhapa soil is found to be polluted with heavy metals such as Cu, Zn, and Pb (highly elevated) and Ti, Cr, Mn, Fe, Ni, and Sr (moderately elevated), compared to the natural countryside soil. These high bulk concentration levels of heavy metals were compared with the Ecological Soil Screening Levels for these elements (U.S. Environment Protection Agency) to assess the potential risk on the immediate biotic environment. Low-Z particle EPMA results showed that the aluminosilicate-containing particles were the most abundant, followed by SiO2, CaCO3-containing, and carbonaceous particles in the Dhapa samples, whereas in the countryside sample only aluminosilicate-containing and SiO2 particles were observed. The mineral particles encountered in the countryside sample are solely of geogenic origin, whereas those from the Dhapa samples seem to have evolved from a mixture of raw dumped MSW, urban dust, and other contributing factors such as wind

  4. Photoelectron imaging, probe of the dynamics: from atoms... to clusters

    International Nuclear Information System (INIS)

    This thesis concerns the study of the deexcitation of clusters and atoms by photoelectron imaging. The first part is dedicated to thermionic emission of a finite size system. A 3-dimensional imaging setup allows us to measure the time evolution of the kinetic energy spectrum of electrons emitted from different clusters (Wn-, Cn-, C60). Then we have a direct access to the fundamental quantities which characterize this statistical emission: the temperature of the finite heat bath and the decay rate. The second part concerns the ionization of atomic Rydberg states placed in a static electric field. We performed the first experiment of photoionization microscopy which allows us to obtain a picture which is the macroscopic projection of the electronic wave function. Then we have access to the detail of the photoionization and particularly to the quantum properties of the electron usually confined at the atomic scale. (author)

  5. Accuracy of analyses of microelectronics nanostructures in atom probe tomography

    Science.gov (United States)

    Vurpillot, F.; Rolland, N.; Estivill, R.; Duguay, S.; Blavette, D.

    2016-07-01

    The routine use of atom probe tomography (APT) as a nano-analysis microscope in the semiconductor industry requires the precise evaluation of the metrological parameters of this instrument (spatial accuracy, spatial precision, composition accuracy or composition precision). The spatial accuracy of this microscope is evaluated in this paper in the analysis of planar structures such as high-k metal gate stacks. It is shown both experimentally and theoretically that the in-depth accuracy of reconstructed APT images is perturbed when analyzing this structure composed of an oxide layer of high electrical permittivity (higher-k dielectric constant) that separates the metal gate and the semiconductor channel of a field emitter transistor. Large differences in the evaporation field between these layers (resulting from large differences in material properties) are the main sources of image distortions. An analytic model is used to interpret inaccuracy in the depth reconstruction of these devices in APT.

  6. Estimation of the reconstruction parameters for Atom Probe Tomography

    CERN Document Server

    Gault, Baptiste; Stephenson, Leigh T; Moody, Michael P; Muddle, Barry C; Ringer, Simon P

    2015-01-01

    The application of wide field-of-view detection systems to atom probe experiments emphasizes the importance of careful parameter selection in the tomographic reconstruction of the analysed volume, as the sensitivity to errors rises steeply with increases in analysis dimensions. In this paper, a self-consistent method is presented for the systematic determination of the main reconstruction parameters. In the proposed approach, the compression factor and the field factor are determined using geometrical projections from the desorption images. A 3D Fourier transform is then applied to a series of reconstructions and, comparing to the known material crystallography, the efficiency of the detector is estimated. The final results demonstrate a significant improvement in the accuracy of the reconstructed volumes.

  7. Atomic force microscope probe-based nanometric scribing

    International Nuclear Information System (INIS)

    Miniaturization of machine components is recognized by many as a significant technological development for a vast spectrum of products. An atomic force microscope (AFM) probe that can exert forces onto a variety of engineering materials is used to perform mechanical scribing at the nanoscale. The success of nanomechanical machining at such fine scales is based on the understanding of microstructural machining mechanics. This paper investigates the cutting behaviour in the nanoscale of a chromium workpiece by using a retrofitted commercial AFM with an acoustic emission sensor, in order to scratch the surface and measure forces. The calibration procedure for acquiring the forces is discussed. The cutting force model, which incorporates the flow stress and friction coefficient in the nano-scale machining, is also presented

  8. Investigation on nanocomposite magnets by three-dimensional atom probe

    Institute of Scientific and Technical Information of China (English)

    WANG Zhanyong; ZHOU Bangxin; NI Jiansen; XU Hui

    2006-01-01

    With the fast development in nano materials, to obtain the detailed microstructure information, microscopes with much higher resolution than the conventional ones are required. A three-dimensional atom probe (3DAP), an instrument with nearatomic resolutions of about 0.06 and 0.2 nm in depth and transverse direction, respectively, has been employed to map out the elemental distribution of some conductive materials within a nano-scale volume.This instrument is fit to analyze the elemental distribution in nano materials and nano precipitation in common materials. 3DAP is applied to investigate the microstructure of Nd2Fe14B/α-Fe nanocomposite magnets. B, Fe-enriched, Zr-enriched and Nd,Fe-enriched clusters have been found, which cannot be identified by any other instrument.

  9. Understanding proton-conducting perovskite interfaces using atom probe tomography

    Science.gov (United States)

    Clark, Daniel R.

    Proton-conducting ceramics are under intense scientific investigation for a number of exciting applications, including fuel cells, electrolyzers, hydrogen separation membranes, membrane reactors, and sensors. However, commercial application requires deeper understanding and improvement of proton conductivity in these materials. It is well-known that proton conductivity in these materials is often limited by highly resistive grain boundaries (GBs). While these conductivity-limiting GBs are still not well understood, it is hypothesized that their blocking nature stems from the formation of a positive (proton-repelling) space-charge zone. Furthermore, it has been observed that the strength of the blocking behavior can change dramatically depending on the fabrication process used to make the ceramic. This thesis applies laser-assisted atom probe tomography (LAAPT) to provide new insights into the GB chemistry and resulting space-charge behavior of BaZr0.9Y0.1O 3--delta (BZY10), a prototypical proton-conducting ceramic. LAAPT is an exciting characterization technique that allows for three-dimensional nm-scale spatial resolution and very high chemical resolution (up to parts-per-million). While it is challenging to quantitatively apply LAAPT to complex, multi-cation oxide materials, this thesis successfully develops a method to accurately quantify the stoichiometry of BZY10 and maintain minimal quantitative cationic deviation at a laser energies of approximately 10--20 pJ. With the analysis technique specifically optimized for BZY10, GB chemistry is then examined for BZY10 samples prepared using four differing processing methods: (1) spark plasma sintering (SPS), (2) conventional sintering using powder prepared by solid-state reaction followed by high-temperature annealing (HT), (3) conventional sintering using powder prepared by solid-state reaction with NiO used as a sintering aid (SSR-Ni), and (4) solid-state reactive sintering directly from BaCO3, ZrO2, and Y2O3

  10. Probing Modified Gravity with Atom-Interferometry: a Numerical Approach

    CERN Document Server

    Schlogel, Sandrine; Fuzfa, Andre

    2015-01-01

    Refined constraints on chameleon theories are calculated for atom-interferometry experiments, using a numerical approach consisting in solving for a four-region model the static and spherically symmetric Klein-Gordon equation for the chameleon field. By modeling not only the test mass and the vacuum chamber but also its walls and the exterior environment, the method allows to probe new effects on the scalar field profile and the induced acceleration of atoms. In the case of a weakly perturbing test mass, the effect of the wall is to enhance the field profile and to lower the acceleration inside the chamber by up to one order of magnitude. In the thin-shell regime, significant deviations from the analytical estimations are found, even when measurements are realized in the immediate vicinity of the test mass. Close to the vacuum chamber wall, the acceleration becomes negative and potentially measurable. This prediction could be used to discriminate between fifth-force effects and systematic experimental uncerta...

  11. Time-of-flight atom probe measurements on Ni3Al and Co3W

    NARCIS (Netherlands)

    Soer, W.A.; Bronsveld, P.M.; Hosson, J.Th.M. De

    2003-01-01

    In this study, a VG FIM100 was taken into operation, consisting of a field-ion microscope (FIM), a time-of-flight atom probe (TOFAP) and an imaging atom probe. A tungsten specimen was used to calibrate the conversion of flight times to m/n values. The resulting relative mass resolution of the TOFAP

  12. Soft-landing ion deposition of isolated radioactive probe atoms on surfaces : A novel method

    NARCIS (Netherlands)

    Laurens, CR; Rosu, MF; Pleiter, F; Niesen, L

    1997-01-01

    We present a method to deposit a wide range of radioactive probe atoms on surfaces, without introducing lattice damage or contaminating the surface with other elements or isotopes. In this method, the probe atoms are mass separated using an isotope separator, decelerated to 5 eV, and directly deposi

  13. Effect of Laser Power on Atom Probe Tomography of Silicates

    Science.gov (United States)

    Parman, S. W.; Gorman, B.; Jackson, C.; Cooper, R. F.; Diercks, D.

    2011-12-01

    Atom probe tomography (APT) is an emerging analytical method that has the potential to produce nm-scale spatial resolution of atom positions with ppm-level detection limits. Until recently, APT has been limited to analysis of conducting samples due to the high pulsed electrical fields previously required. The recent development of laser-assisted APT now allows much lower laser powers to be used, opening the door to analysis of geologic minerals. The potential applications are many, ranging from diffusion profiles to the distribution of nano-phases to grain boundary chemical properties. We reported the first analysis of natural olivine using APT last year (Parman et al, 2010). While the spatial resolution was good (nm-scale), the accuracy of the compositional analysis was not. Two of the primary barriers to accurate ion identification in APT are: 1) Specimen overheating - This is caused by the interaction of the laser with the low thermal conductivity insulating specimens. Ions are assumed to have left the surface of the sample at the time the laser is pulsed during the analysis (laser pulse width = 12 ps). If the laser power is too high, the surface remains heated for an appreciable time (greater than 5 ns in some cases) after the laser pulse, causing atoms to field evaporate from the surface well after the laser pulse. Since they hit the detector later than the atoms that were released during the pulse, they are interpreted to be higher mass. Thus overheating appears in the analysis as a smearing of mass/charge peaks to higher mass/charge ratios (thermal tails). For well separated peaks, this is not a substantial problem, but for closely spaced peaks, overheating causes artificial mass interferences. 2) Molecular evaporation or clustering - This is also caused by overheating by the laser. Ideally, atoms are field evaporated individually from the surface of the cylindrical specimen. However, if the absorbed energy is high enough, clusters of atoms will be formed

  14. Atom probe tomography of stress corrosion crack tips in SUS316 stainless steels

    International Nuclear Information System (INIS)

    Highlights: • Quantitative study of 3D features such as grain boundary oxides and Ni enrichment. • Features can be related to their distance from the crack tip. • Local measurement of compositions in very small volumes and specific regions. • Complementary analytical TEM data was recorded to correlate to APT results. • Both matrix elements (Fe, Cr, Ni) and oxygen diffuse along the grain boundary. - Abstract: Novel atom probe tomography (APT) data of an intergranular stress corrosion crack tip has been acquired. Using APT for stress corrosion cracking research, very small, localized features and their distribution around the crack tip can be studied in 3D. This work details the development of a technique for the preparation of atom probe needles. Initial characterization via analytical transmission electron microscopy provides with a complementary analysis and accurately locates features that can be correlated with the reconstructed APT data. Ni enrichment and intergranular oxidation ahead of the crack tip have been studied with APT in 3D and with near-atomic resolution

  15. Nanometer-scale isotope analysis of bulk diamond by atom probe tomography

    NARCIS (Netherlands)

    Schirhagl, R.; Raatz, N.; Meijer, J.; Markham, M.; Gerstl, S. S. A.; Degen, C. L.

    2015-01-01

    Atom-probe tomography (APT) combines field emission of atoms with mass spectrometry to reconstruct three-dimensional tomograms of materials with atomic resolution and isotope specificity. Despite significant recent progress in APT technology, application to wide-bandgap materials with strong covalen

  16. C12/C13-ratio determination in nanodiamonds by atom-probe tomography.

    Science.gov (United States)

    Lewis, Josiah B; Isheim, Dieter; Floss, Christine; Seidman, David N

    2015-12-01

    The astrophysical origins of ∼ 3 nm-diameter meteoritic nanodiamonds can be inferred from the ratio of C12/C13. It is essential to achieve high spatial and mass resolving power and minimize all sources of signal loss in order to obtain statistically significant measurements. We conducted atom-probe tomography on meteoritic nanodiamonds embedded between layers of Pt. We describe sample preparation, atom-probe tomography analysis, 3D reconstruction, and bias correction. We present new data from meteoritic nanodiamonds and terrestrial standards and discuss methods to correct isotopic measurements made with the atom-probe tomograph.

  17. Quantitative dopant distributions in GaAs nanowires using atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Du, Sichao [School of Physics, The University of Sydney, NSW 2006 (Australia); Burgess, Timothy [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Gault, Baptiste [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Department of Materials Science and Engineering, McMaster University, 1280 Main St W, Hamilton, Ontario L8S4L8 (Canada); Gao, Qiang [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Bao, Peite; Li, Li [School of Physics, The University of Sydney, NSW 2006 (Australia); Cui, Xiangyuan; Kong Yeoh, Wai; Liu, Hongwei; Yao, Lan [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Ceguerra, Anna V. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Hoe Tan, Hark; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Ringer, Simon P. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Zheng, Rongkun, E-mail: rongkun.zheng@sydney.edu.au [School of Physics, The University of Sydney, NSW 2006 (Australia)

    2013-09-15

    Controllable doping of semiconductor nanowires is critical to realize their proposed applications, however precise and reliable characterization of dopant distributions remains challenging. In this article, we demonstrate an atomic-resolution three-dimensional elemental mapping of pristine semiconductor nanowires on growth substrates by using atom probe tomography to tackle this major challenge. This highly transferrable method is able to analyze the full diameter of a nanowire, with a depth resolution better than 0.17 nm thanks to an advanced reconstruction method exploiting the specimen's crystallography, and an enhanced chemical sensitivity of better than 8-fold increase in the signal-to-noise ratio. - Highlights: ► Probing pristine semiconductor NWs from growth substrate has been demonstrated. ► Analyzing the full diameter of a nanowire has been achieved. ► A spatial resolution better than 0.17 nm in depth has been obtained for GaAs. ► An enhanced SNR 100:2 has been achieved.

  18. Quantitative dopant distributions in GaAs nanowires using atom probe tomography

    International Nuclear Information System (INIS)

    Controllable doping of semiconductor nanowires is critical to realize their proposed applications, however precise and reliable characterization of dopant distributions remains challenging. In this article, we demonstrate an atomic-resolution three-dimensional elemental mapping of pristine semiconductor nanowires on growth substrates by using atom probe tomography to tackle this major challenge. This highly transferrable method is able to analyze the full diameter of a nanowire, with a depth resolution better than 0.17 nm thanks to an advanced reconstruction method exploiting the specimen's crystallography, and an enhanced chemical sensitivity of better than 8-fold increase in the signal-to-noise ratio. - Highlights: ► Probing pristine semiconductor NWs from growth substrate has been demonstrated. ► Analyzing the full diameter of a nanowire has been achieved. ► A spatial resolution better than 0.17 nm in depth has been obtained for GaAs. ► An enhanced SNR 100:2 has been achieved

  19. Atom probe field ion microscopy and related topics: A bibliography 1991

    International Nuclear Information System (INIS)

    This report contains a bibliography for 1991 on the following topics: Atom probe field ion microscopy; field desorption mass spectrometry; field emission; field ion microscopy; and field emission theory

  20. Atom Probe Insights into U-Pb Age Resetting in Baddeleyite

    Science.gov (United States)

    White, L. F.; Reinhard, D.; Moser, D.; Darling, J. R.; Bullen, D.; Prosa, T. J.; Olson, D.; Larson, D. J.; Clifton, P. H.; Lawrence, D.; Martin, I.

    2016-08-01

    Atom probe analysis of highly shocked baddeleyite suggests that igneous crystallisation ages can be isolated from 'partially reset' grains through careful segregation and rejection of planar features known to induce post-impact Pb-diffusion.

  1. Atom probe field ion microscopy and related topics: A bibliography 1991

    Energy Technology Data Exchange (ETDEWEB)

    Russell, K.F.; Miller, M.K.

    1993-01-01

    This report contains a bibliography for 1991 on the following topics: Atom probe field ion microscopy; field desorption mass spectrometry; field emission; field ion microscopy; and field emission theory.

  2. Solid-state electrochemistry on the nanometer and atomic scales: the scanning probe microscopy approach

    Science.gov (United States)

    Strelcov, Evgheni; Yang, Sang Mo; Jesse, Stephen; Balke, Nina; Vasudevan, Rama K.; Kalinin, Sergei V.

    2016-07-01

    Energy technologies of the 21st century require an understanding and precise control over ion transport and electrochemistry at all length scales - from single atoms to macroscopic devices. This short review provides a summary of recent studies dedicated to methods of advanced scanning probe microscopy for probing electrochemical transformations in solids at the meso-, nano- and atomic scales. The discussion presents the advantages and limitations of several techniques and a wealth of examples highlighting peculiarities of nanoscale electrochemistry.

  3. Characterizing nanoscale scanning probes using electron microscopy: A novel fixture and a practical guide

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Tevis D. B., E-mail: tjacobs@pitt.edu [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 3700 O’Hara St., Pittsburgh, Pennsylvania 15208 (United States); Wabiszewski, Graham E.; Goodman, Alexander J.; Carpick, Robert W., E-mail: carpick@seas.upenn.edu [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 220 S. 33rd St., Philadelphia, Pennsylvania 19104 (United States)

    2016-01-15

    The nanoscale geometry of probe tips used for atomic force microscopy (AFM) measurements determines the lateral resolution, contributes to the strength of the tip-surface interaction, and can be a significant source of uncertainty in the quantitative analysis of results. While inverse imaging of the probe tip has been used successfully to determine probe tip geometry, direct observation of the tip profile using electron microscopy (EM) confers several advantages: it provides direct (rather than indirect) imaging, requires fewer algorithmic parameters, and does not require bringing the tip into contact with a sample. In the past, EM-based observation of the probe tip has been achieved using ad hoc mounting methods that are constrained by low throughput, the risk of contamination, and repeatability issues. We report on a probe fixture designed for use in a commercial transmission electron microscope that enables repeatable mounting of multiple AFM probes as well as a reference grid for beam alignment. This communication describes the design, fabrication, and advantages of this probe fixture, including full technical drawings for machining. Further, best practices are discussed for repeatable, non-destructive probe imaging. Finally, examples of the fixture’s use are described, including characterization of common commercial AFM probes in their out-of-the-box condition.

  4. Characterizing nanoscale scanning probes using electron microscopy: A novel fixture and a practical guide

    Science.gov (United States)

    Jacobs, Tevis D. B.; Wabiszewski, Graham E.; Goodman, Alexander J.; Carpick, Robert W.

    2016-01-01

    The nanoscale geometry of probe tips used for atomic force microscopy (AFM) measurements determines the lateral resolution, contributes to the strength of the tip-surface interaction, and can be a significant source of uncertainty in the quantitative analysis of results. While inverse imaging of the probe tip has been used successfully to determine probe tip geometry, direct observation of the tip profile using electron microscopy (EM) confers several advantages: it provides direct (rather than indirect) imaging, requires fewer algorithmic parameters, and does not require bringing the tip into contact with a sample. In the past, EM-based observation of the probe tip has been achieved using ad hoc mounting methods that are constrained by low throughput, the risk of contamination, and repeatability issues. We report on a probe fixture designed for use in a commercial transmission electron microscope that enables repeatable mounting of multiple AFM probes as well as a reference grid for beam alignment. This communication describes the design, fabrication, and advantages of this probe fixture, including full technical drawings for machining. Further, best practices are discussed for repeatable, non-destructive probe imaging. Finally, examples of the fixture's use are described, including characterization of common commercial AFM probes in their out-of-the-box condition.

  5. Characterizing nanoscale scanning probes using electron microscopy: A novel fixture and a practical guide

    International Nuclear Information System (INIS)

    The nanoscale geometry of probe tips used for atomic force microscopy (AFM) measurements determines the lateral resolution, contributes to the strength of the tip-surface interaction, and can be a significant source of uncertainty in the quantitative analysis of results. While inverse imaging of the probe tip has been used successfully to determine probe tip geometry, direct observation of the tip profile using electron microscopy (EM) confers several advantages: it provides direct (rather than indirect) imaging, requires fewer algorithmic parameters, and does not require bringing the tip into contact with a sample. In the past, EM-based observation of the probe tip has been achieved using ad hoc mounting methods that are constrained by low throughput, the risk of contamination, and repeatability issues. We report on a probe fixture designed for use in a commercial transmission electron microscope that enables repeatable mounting of multiple AFM probes as well as a reference grid for beam alignment. This communication describes the design, fabrication, and advantages of this probe fixture, including full technical drawings for machining. Further, best practices are discussed for repeatable, non-destructive probe imaging. Finally, examples of the fixture’s use are described, including characterization of common commercial AFM probes in their out-of-the-box condition

  6. Nanomechanical and topographical imaging of living cells by atomic force microscopy with colloidal probes

    Energy Technology Data Exchange (ETDEWEB)

    Puricelli, Luca; Galluzzi, Massimiliano; Schulte, Carsten; Podestà, Alessandro, E-mail: alessandro.podesta@mi.infn.it; Milani, Paolo [CIMaINa and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy)

    2015-03-15

    Atomic Force Microscopy (AFM) has a great potential as a tool to characterize mechanical and morphological properties of living cells; these properties have been shown to correlate with cells’ fate and patho-physiological state in view of the development of novel early-diagnostic strategies. Although several reports have described experimental and technical approaches for the characterization of cellular elasticity by means of AFM, a robust and commonly accepted methodology is still lacking. Here, we show that micrometric spherical probes (also known as colloidal probes) are well suited for performing a combined topographic and mechanical analysis of living cells, with spatial resolution suitable for a complete and accurate mapping of cell morphological and elastic properties, and superior reliability and accuracy in the mechanical measurements with respect to conventional and widely used sharp AFM tips. We address a number of issues concerning the nanomechanical analysis, including the applicability of contact mechanical models and the impact of a constrained contact geometry on the measured Young’s modulus (the finite-thickness effect). We have tested our protocol by imaging living PC12 and MDA-MB-231 cells, in order to demonstrate the importance of the correction of the finite-thickness effect and the change in Young’s modulus induced by the action of a cytoskeleton-targeting drug.

  7. Atomic scale properties of magnetic Mn-based alloys probed by emission Mössbauer spectroscopy

    CERN Multimedia

    Mn-based alloys are characterized by a wealth of properties, which are of interest both from fundamental physics point of view and particularly attractive for different applications in modern technology: from magnetic storage to sensing and spin-based electronics. The possibility to tune their magnetic properties through post-growth thermal processes and/or stoichiometry engineering is highly important in order to target different applications (i.e. Mn$_{x}$Ga) or to increase their Curie temperature above room temperature (i.e. off-stoichiometric MnSi). In this project, the Mössbauer effect will be applied at $^{57}$Fe sites following implantation of radioactive $^{57}$Mn, to probe the micro-structure and magnetism of Mn-based alloys on the atomic-scale. The proposed experimental plan is devoted to establish a direct correlation between the local structure and bulk magnetism (and other physical properties) of Mn-based alloys.

  8. Atomic quantum superposition state generation via optical probing

    DEFF Research Database (Denmark)

    Nielsen, Anne Ersbak Bang; Poulsen, Uffe Vestergaard; Negretti, Antonio;

    2009-01-01

    We analyze the performance of a protocol to prepare an atomic ensemble in a superposition of two macroscopically distinguishable states. The protocol relies on conditional measurements performed on a light field, which interacts with the atoms inside an optical cavity prior to detection, and we...

  9. Probing angular momentum coherence in a twin-atom interferometer

    CERN Document Server

    de Carvalho, Carlos R; Impens, François; Robert, J; Medina, Aline; Zappa, F; Faria, N V de Castro

    2014-01-01

    We propose to use a double longitudinal Stern-Gerlach atom interferometer in order to investigate quantitatively the angular momentum coherence of molecular fragments. Assuming that the dissociated molecule has a null total angular momentum, we investigate the propagation of the corresponding atomic fragments in the apparatus. We show that the envisioned interferometer enables one to distinguish unambiguously a spin-coherent from a spin-incoherent dissociation, as well as to estimate the purity of the angular momentum density matrix associated with the fragments. This setup, which may be seen as an atomic analogue of a twin-photon interferometer, can be used to investigate the suitability of molecule dissociation processes -- such as the metastable hydrogen atoms H($2^2 S$)-H($2^2 S$) dissociation - for coherent twin-atom optics.

  10. Dopant distributions in n-MOSFET structure observed by atom probe tomography.

    Science.gov (United States)

    Inoue, K; Yano, F; Nishida, A; Takamizawa, H; Tsunomura, T; Nagai, Y; Hasegawa, M

    2009-11-01

    The dopant distributions in an n-type metal-oxide-semiconductor field effect transistor (MOSFET) structure were analyzed by atom probe tomography. The dopant distributions of As, P, and B atoms in a MOSFET structure (gate, gate oxide, channel, source/drain extension, and halo) were obtained. P atoms were segregated at the interface between the poly-Si gate and the gate oxide, and on the grain boundaries of the poly-Si gate, which had an elongated grain structure along the gate height direction. The concentration of B atoms was enriched near the edge of the source/drain extension where the As atoms were implanted. PMID:19775815

  11. Dopant distributions in n-MOSFET structure observed by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, K., E-mail: koji.inoue@hs3.ecs.kyoto-u.ac.jp [The Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Yano, F.; Nishida, A. [MIRAI-Selete, Tsukuba, Ibaraki 305-8569 (Japan); Takamizawa, H. [The Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Tsunomura, T. [MIRAI-Selete, Tsukuba, Ibaraki 305-8569 (Japan); Nagai, Y. [The Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Hasegawa, M. [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Cyclotron and Radioisotope Center, Tohoku University, Sendai 980-8578 (Japan)

    2009-11-15

    The dopant distributions in an n-type metal-oxide-semiconductor field effect transistor (MOSFET) structure were analyzed by atom probe tomography. The dopant distributions of As, P, and B atoms in a MOSFET structure (gate, gate oxide, channel, source/drain extension, and halo) were obtained. P atoms were segregated at the interface between the poly-Si gate and the gate oxide, and on the grain boundaries of the poly-Si gate, which had an elongated grain structure along the gate height direction. The concentration of B atoms was enriched near the edge of the source/drain extension where the As atoms were implanted.

  12. Bragg scattering as a probe of atomic wave functions and quantum phase transitions in optical lattices.

    Science.gov (United States)

    Miyake, Hirokazu; Siviloglou, Georgios A; Puentes, Graciana; Pritchard, David E; Ketterle, Wolfgang; Weld, David M

    2011-10-21

    We have observed Bragg scattering of photons from quantum degenerate ^{87}Rb atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wave function whose position and momentum width is Heisenberg limited. The spatial coherence of the wave function leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence. PMID:22107532

  13. Scanned probe characterization of semiconductor nanostructures

    OpenAIRE

    Law, James Jeremy MacDonald

    2009-01-01

    Advances in the synthesis of materials and device structures have accentuated the need to understand nanoscale electronic structure and its implications. Scanning probe microscopy offers a rich variety of highly spatially accurate techniques that can further our understanding of the interactions that occur in nanoscale semiconductor materials and devices. The promising nitride semiconductor materials system suffers from perturbations in local electronic structure due to crystallographic defec...

  14. Probing the Planck Scale in Low-Energy Atomic Physics

    OpenAIRE

    Bluhm, Robert

    2001-01-01

    Experiments in atomic physics have exceptional sensitivity to small shifts in energy in an atom, ion, or bound particle. They are particularly well suited to search for unique low-energy signatures of new physics, including effects that could originate from the Planck scale. A number of recent experiments have used CPT and Lorentz violation as a candidate signal of new physics originating from the Planck scale. A discussion of these experiments and their theoretical implications is presented.

  15. Restoring the lattice of Si-based atom probe reconstructions for enhanced information on dopant positioning.

    Science.gov (United States)

    Breen, Andrew J; Moody, Michael P; Ceguerra, Anna V; Gault, Baptiste; Araullo-Peters, Vicente J; Ringer, Simon P

    2015-12-01

    The following manuscript presents a novel approach for creating lattice based models of Sb-doped Si directly from atom probe reconstructions for the purposes of improving information on dopant positioning and directly informing quantum mechanics based materials modeling approaches. Sophisticated crystallographic analysis techniques are used to detect latent crystal structure within the atom probe reconstructions with unprecedented accuracy. A distortion correction algorithm is then developed to precisely calibrate the detected crystal structure to the theoretically known diamond cubic lattice. The reconstructed atoms are then positioned on their most likely lattice positions. Simulations are then used to determine the accuracy of such an approach and show that improvements to short-range order measurements are possible for noise levels and detector efficiencies comparable with experimentally collected atom probe data.

  16. Investigation of material property influenced stoichiometric deviations as evidenced during UV laser-assisted atom probe tomography in fluorite oxides

    Energy Technology Data Exchange (ETDEWEB)

    Valderrama, Billy; Henderson, Hunter B. [Department of Materials Science and Engineering, University of Florida, 100 Rhines Hall, Gainesville, FL 32611 (United States); Yablinsky, Clarissa A. [Department of Nuclear Engineering, University of Wisconsin-Madison, 921 ERB, 1500 Engineering Drive, Madison, WI 53706 (United States); Gan, Jian [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States); Allen, Todd R. [Department of Nuclear Engineering, University of Wisconsin-Madison, 921 ERB, 1500 Engineering Drive, Madison, WI 53706 (United States); Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States); Manuel, Michele V., E-mail: mmanuel@mse.ufl.edu [Department of Materials Science and Engineering, University of Florida, 100 Rhines Hall, Gainesville, FL 32611 (United States)

    2015-09-15

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO{sub 2}) and uranium oxide (UO{sub 2}) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  17. Investigation of material property influenced stoichiometric deviations as evidenced during UV laser-assisted atom probe tomography in fluorite oxides

    Science.gov (United States)

    Valderrama, Billy; Henderson, Hunter B.; Yablinsky, Clarissa A.; Gan, Jian; Allen, Todd R.; Manuel, Michele V.

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  18. State Feedback Control for Adjusting the Dynamic Behavior of a Piezoactuated Bimorph Atomic Force Microscopy Probe

    CERN Document Server

    Orun, Bilal; Basdogan, Cagatay; Guvenc, Levent

    2012-01-01

    We adjust the transient dynamics of a piezo-actuated bimorph Atomic Force Microscopy (AFM) probe using a state feedback controller. This approach enables us to adjust the quality factor and the resonance frequency of the probe simultaneously. First, we first investigate the effect of feedback gains on dynamic response of the probe and then show that the time constant of the probe can be reduced by reducing its quality factor and/or increasing its resonance frequency to reduce the scan error in tapping mode AFM.

  19. Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wanghua; Roca i Cabarrocas, Pere [Laboratoire de Physique des Interfaces et Couches Minces (LPICM), UMR 7647, CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Pareige, Philippe; Castro, Celia [Groupe de Physique des Matériaux (GPM), Université et INSA de Rouen, UMR 6634, CNRS, Av. de l' Université, BP 12, 76801 Saint Etienne du Rouvray (France); Xu, Tao; Grandidier, Bruno; Stiévenard, Didier [Institut d' Electronique et de Microélectronique et de Nanotechnologies (IEMN), UMR 8520, CNRS, Département ISEN, 41 bd Vauban, 59046 Lille Cedex (France)

    2015-09-14

    By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.

  20. Atom probe tomographic study of elemental segregation at grain boundaries for a peak-aged Al–Zn–Mg alloy

    International Nuclear Information System (INIS)

    Highlights: •Atom probe tomography is used to characterize the solute segregation at GBs. •Mg segregates at GBs within 3 nm for a peak-aged Al–Zn–Mg alloy. •Zn does not segregate at GBs. •MgZn2 precipitates are not the H trapping sites, but Mg2Si precipitates are. •Clusters containing Zn, H and oxides have been found at GBs. -- Abstract: Atom probe tomography (APT) has been used to characterize the element segregation at the grain boundary (GB) for a peak-aged Al–Zn–Mg alloy with high stress corrosion cracking (SCC) susceptibility. The results show that Mg segregates along the GB with a peak concentration of 1.38 at.% and width of 3 nm. Zn does not segregate at GB. However, segregation of Zn and H atoms at oxide-containing clusters on GB has been observed. APT atom maps also reveal that Mg2Si is the H trapping site, but MgZn2 is not

  1. IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY(AFM)

    Institute of Scientific and Technical Information of China (English)

    XU Zongwei; DONG Shen; GUO Liqiu; ZHAO Qingliang

    2006-01-01

    An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy (AFM) here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function.Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication's difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe.

  2. Nanogeochronology of discordant zircon measured by atom probe microscopy of Pb-enriched dislocation loops.

    Science.gov (United States)

    Peterman, Emily M; Reddy, Steven M; Saxey, David W; Snoeyenbos, David R; Rickard, William D A; Fougerouse, Denis; Kylander-Clark, Andrew R C

    2016-09-01

    Isotopic discordance is a common feature in zircon that can lead to an erroneous age determination, and it is attributed to the mobilization and escape of radiogenic Pb during its post-crystallization geological evolution. The degree of isotopic discordance measured at analytical scales of ~10 μm often differs among adjacent analysis locations, indicating heterogeneous distributions of Pb at shorter length scales. We use atom probe microscopy to establish the nature of these sites and the mechanisms by which they form. We show that the nanoscale distribution of Pb in a ~2.1 billion year old discordant zircon that was metamorphosed c. 150 million years ago is defined by two distinct Pb reservoirs. Despite overall Pb loss during peak metamorphic conditions, the atom probe data indicate that a component of radiogenic Pb was trapped in 10-nm dislocation loops that formed during the annealing of radiation damage associated with the metamorphic event. A second Pb component, found outside the dislocation loops, represents homogeneous accumulation of radiogenic Pb in the zircon matrix after metamorphism. The (207)Pb/(206)Pb ratios measured from eight dislocation loops are equivalent within uncertainty and yield an age consistent with the original crystallization age of the zircon, as determined by laser ablation spot analysis. Our results provide a specific mechanism for the trapping and retention of radiogenic Pb during metamorphism and confirm that isotopic discordance in this zircon is characterized by discrete nanoscale reservoirs of Pb that record different isotopic compositions and yield age data consistent with distinct geological events. These data may provide a framework for interpreting discordance in zircon as the heterogeneous distribution of discrete radiogenic Pb populations, each yielding geologically meaningful ages.

  3. Probing and controlling quantum magnetism with ultra-cold atoms

    Science.gov (United States)

    Rey, Ana Maria

    2008-05-01

    By loading spinor atoms in optical lattices it is now possible to experimentally implement quantum spin models in a controlled environment, and to investigate quantum magnetism in strongly correlated systems. In this talk we will describe a novel approach to prepare, detect and control super-exchange interactions in ultracold spinor atoms loaded in optical superlattices [1]. Recently this approach was used for the first experimental observation of super-exchange interactions in ultra-cold atoms [2]. The many-body dynamics arising from the coherent coupling between singlet-triplet pairs in adjacent double-wells will be also discussed, in particular how it can lead to the formation of spin states with a high degree of multi-particle entanglement. Finally, we will present an extension of this approach to prepare and detect in a controllable way d-wave superfluidity in an array of weakly coupled plaquettes loaded with fermionic atoms. [1] A. M. Rey, V. Gritsev,I. Bloch, E. Demler, and M. D. Lukin, PRL 99, 140601 (2007) [2] S. Trotzky, P. Cheinet, S. Folling, M. Feld, U. Schnorrberger, A.M. Rey, A. Polkovnikov, E. Demler, M. D. Lukin, and I. Bloch, Science 319, 295 (2008)

  4. The multipole resonance probe: characterization of a prototype

    Energy Technology Data Exchange (ETDEWEB)

    Lapke, Martin; Oberrath, Jens; Brinkmann, Ralf Peter; Mussenbrock, Thomas [Lehrstuhl fuer Theoretische Elektrotechnik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Schulz, Christian; Rolfes, Ilona [Lehrstuhl fuer Hochfrequenzsysteme, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Storch, Robert; Musch, Thomas [Lehrstuhl fuer Elektronische Schaltungstechnik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Styrnoll, Tim; Awakowicz, Peter [Lehrstuhl fuer Allgemeine Elektrotechnik und Plasmatechnik, Ruhr Universitaet Bochum, D-44780 Bochum (Germany); Zietz, Christian [Institut fuer Hochfrequenztechnik und Funksysteme, Leibniz Universitaet Hannover, D-30167 Hannover (Germany)

    2011-08-15

    The multipole resonance probe (MRP) was recently proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2008 Appl. Phys. Lett. 93 051502). This communication reports the experimental characterization of a first MRP prototype in an inductively coupled argon/nitrogen plasma at 10 Pa. The behavior of the device follows the predictions of both an analytical model and a numerical simulation. The obtained electron densities are in excellent agreement with the results of Langmuir probe measurements. (brief communication)

  5. Noncontact atomic force and Kelvin probe force microscopy on MgO(100) and MgO(100)-supported Ba

    Science.gov (United States)

    Pang, Chi Lun; Sasahara, Akira; Onishi, Hiroshi

    2016-08-01

    Atomically-flat MgO(100) surfaces were prepared by sputtering and annealing. Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) were used to characterize the MgO(100) surfaces. The NC-AFM images revealed the presence of point defects on an atomically-resolved surface. The surface potential at these point defects, as well as features such as step edges and deposited Ba nanoparticles were mapped using KPFM. The Kelvin images show that the surface potential increases at the point defects and at the step edges. On the other hand, a decrease in the potential was found over Ba nanoparticles which can be explained by electron charge transfer from the Ba to the MgO.

  6. Preparation and Analysis of Atom Probe Tips by Xenon Focused Ion Beam Milling.

    Science.gov (United States)

    Estivill, Robert; Audoit, Guillaume; Barnes, Jean-Paul; Grenier, Adeline; Blavette, Didier

    2016-06-01

    The damage and ion distribution induced in Si by an inductively coupled plasma Xe focused ion beam was investigated by atom probe tomography. By using predefined patterns it was possible to prepare the atom probe tips with a sub 50 nm end radius in the ion beam microscope. The atom probe reconstruction shows good agreement with simulated implantation profiles and interplanar distances extracted from spatial distribution maps. The elemental profiles of O and C indicate co-implantation during the milling process. The presence of small disc-shaped Xe clusters are also found in the three-dimensional reconstruction. These are attributed to the presence of Xe nanocrystals or bubbles that open during the evaporation process. The expected accumulated dose points to a loss of >95% of the Xe during analysis, which escapes undetected.

  7. Atomic resolution in noncontact AFM by probing cantilever frequency shifts

    Institute of Scientific and Technical Information of China (English)

    Hong Yong Xie

    2007-01-01

    Rutile TiO2(001) quantum dots (or nano-marks) in different shapes were used to imitate uncleaved material surfaces or materials with rough surfaces. By numerical integration of the equation of motion of cantilever for silicon tip scanning along the [110] direction over the rutile TiO2 (001) quantum dots in ultra high vacuum (UHV), scanning routes were explored to achieve atomic resolution from frequency shift image. The tip-surface interaction forces were calculated from Lennard-Jones (12-6) potential by the Hamaker summation method. The calculated results showed that atomic resolution could be achieved by frequency shift image for TiO2 (001) surfaces of rhombohedral quantum dot scanning in a vertical route, and spherical cap quantum dot scanning in a superposition route.

  8. Tailored probes for atomic force microscopy fabricated by two-photon polymerization

    Science.gov (United States)

    Göring, Gerald; Dietrich, Philipp-Immanuel; Blaicher, Matthias; Sharma, Swati; Korvink, Jan G.; Schimmel, Thomas; Koos, Christian; Hölscher, Hendrik

    2016-08-01

    3D direct laser writing based on two-photon polymerization is considered as a tool to fabricate tailored probes for atomic force microscopy. Tips with radii of 25 nm and arbitrary shape are attached to conventionally shaped micro-machined cantilevers. Long-term scanning measurements reveal low wear rates and demonstrate the reliability of such tips. Furthermore, we show that the resonance spectrum of the probe can be tuned for multi-frequency applications by adding rebar structures to the cantilever.

  9. A versatile LabVIEW and FPGA-based scanned probe microscope for in-operando electronic device characterization

    OpenAIRE

    Berger, Andrew J.; Page, Michael R.; Jacob, Jan; Young, Justin R.; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P.; Johnston-Halperin, Ezekiel; Pelekhov, Denis V.; Hammel, P. Chris

    2014-01-01

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In-operando characterization of such devices by scanned probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanned probe microscope (SPM) which is capable of both standard force imaging (atomic, magnet...

  10. Atom-scale compositional distribution in InAlAsSb-based triple junction solar cells by atom probe tomography.

    Science.gov (United States)

    Hernández-Saz, J; Herrera, M; Delgado, F J; Duguay, S; Philippe, T; Gonzalez, M; Abell, J; Walters, R J; Molina, S I

    2016-07-29

    The analysis by atom probe tomography (APT) of InAlAsSb layers with applications in triple junction solar cells (TJSCs) has shown the existence of In- and Sb-rich regions in the material. The composition variation found is not evident from the direct observation of the 3D atomic distribution and because of this a statistical analysis has been required. From previous analysis of these samples, it is shown that the small compositional fluctuations determined have a strong effect on the optical properties of the material and ultimately on the performance of TJSCs. PMID:27306098

  11. Atom-scale compositional distribution in InAlAsSb-based triple junction solar cells by atom probe tomography

    Science.gov (United States)

    Hernández-Saz, J.; Herrera, M.; Delgado, F. J.; Duguay, S.; Philippe, T.; Gonzalez, M.; Abell, J.; Walters, R. J.; Molina, S. I.

    2016-07-01

    The analysis by atom probe tomography (APT) of InAlAsSb layers with applications in triple junction solar cells (TJSCs) has shown the existence of In- and Sb-rich regions in the material. The composition variation found is not evident from the direct observation of the 3D atomic distribution and because of this a statistical analysis has been required. From previous analysis of these samples, it is shown that the small compositional fluctuations determined have a strong effect on the optical properties of the material and ultimately on the performance of TJSCs.

  12. A new systematic framework for crystallographic analysis of atom probe data

    Energy Technology Data Exchange (ETDEWEB)

    Araullo-Peters, Vicente J., E-mail: vicente.araullopeters@gmail.com [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia); Breen, Andrew; Ceguerra, Anna V. [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia); Gault, Baptiste [Department of Materials, University of Oxford, Parks Road, Oxford (United Kingdom); Ringer, Simon P.; Cairney, Julie M. [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia)

    2015-07-15

    In this article, after a brief introduction to the principles behind atom probe crystallography, we introduce methods for unambiguously determining the presence of crystal planes within atom probe datasets, as well as their characteristics: location; orientation and interplanar spacing. These methods, which we refer to as plane orientation extraction (POE) and local crystallography mapping (LCM) make use of real-space data and allow for systematic analyses. We present here application of POE and LCM to datasets of pure Al, industrial aluminium alloys and doped-silicon. Data was collected both in DC voltage mode and laser-assisted mode (in the latter of which extracting crystallographic information is known to be more difficult due to distortions). The nature of the atomic planes in both datasets was extracted and analysed. - Highlights: • A new analysis method was designed that determines if reconstructed planes are present in atom probe data. • The location, orientation, and planar spacing of these planes are obtained. • This method was applied to simulated, aluminium alloy and silicon data where the extent of planes was shown to vary considerably. • This method can be used to examine atom probe reconstruction quality.

  13. A new systematic framework for crystallographic analysis of atom probe data

    International Nuclear Information System (INIS)

    In this article, after a brief introduction to the principles behind atom probe crystallography, we introduce methods for unambiguously determining the presence of crystal planes within atom probe datasets, as well as their characteristics: location; orientation and interplanar spacing. These methods, which we refer to as plane orientation extraction (POE) and local crystallography mapping (LCM) make use of real-space data and allow for systematic analyses. We present here application of POE and LCM to datasets of pure Al, industrial aluminium alloys and doped-silicon. Data was collected both in DC voltage mode and laser-assisted mode (in the latter of which extracting crystallographic information is known to be more difficult due to distortions). The nature of the atomic planes in both datasets was extracted and analysed. - Highlights: • A new analysis method was designed that determines if reconstructed planes are present in atom probe data. • The location, orientation, and planar spacing of these planes are obtained. • This method was applied to simulated, aluminium alloy and silicon data where the extent of planes was shown to vary considerably. • This method can be used to examine atom probe reconstruction quality

  14. Atomic-scale investigations of grain boundary segregation in astrology with a three dimensional atom-probe

    Energy Technology Data Exchange (ETDEWEB)

    Blavette, D. [Rouen Univ., 76 - Mont-Saint-Aignan (France). Lab. de Microscopie Electronique]|[Institut Universitaire de France (France); Letellier, L. [Rouen Univ., 76 - Mont-Saint-Aignan (France). Lab. de Microscopie Electronique; Duval, P. [Rouen Univ., 76 - Mont-Saint-Aignan (France). Lab. de Microscopie Electronique; Guttmann, M. [Rouen Univ., 76 - Mont-Saint-Aignan (France). Lab. de Microscopie Electronique]|[Institut de Recherches de la Siderurgie Francaise (IRSID), 57 - Maizieres-les-Metz (France)

    1996-08-01

    Both conventional and 3D atom-probes were applied to the investigation of grain-boundary (GB) segregation phenomena in two-phase nickel base superalloys Astroloy. 3D images as provided by the tomographic atom-probe reveal the presence of a strong segregation of both boron and molybdenum at grain-boundaries. Slight carbon enrichment is also detected. Considerable chromium segregation is exhibited at {gamma}`-{gamma}` grain-boundaries. All these segregants are distributed in a continuous manner along the boundary over a width close to 0.5 nm. Experiments show that segregation occurs during cooling and more probably between 1000 C and 800 C. Boron and molybdenum GB enrichments are interpreted as due to an equilibrium type-segregation while chromium segregation is thought to be induced by {gamma}` precipitation at GB`s and stabilised by the presence of boron. No segregation of zirconium is detected. (orig.)

  15. Characterization of axial probes used in eddy current testing

    International Nuclear Information System (INIS)

    Customized reference tubes reduced sensitivity discrepancies able to be observed from one probe to the other, due to the gain setting adjustment required for a pre-definite level in amplitude response of the artificial notch. The use of a reference circuit in place of a reference part, makes characterization of the probe matched to its generator more accurate: - the material dependence is cancelled during the compensation process, - the reference signal can be adjusted more accurately in amplitude and phase response, - the manufacturing cost is reduced compared to the one necessary for machining the reference part, - the amplitude and phase response of the reference circuit can be simply modelled by using the transformer relations, such as one can appreciate the variations of the probe definition parameters and its connexion to the generator, and makes them optimal for use. The method proposed by ALSTOM for the characterization of the condenser and exchanger tubing probes, takes in account the amplitude and phase response of a reference circuit versus frequency, such it can be done by using SURECA tubing provided by ASCOT: it allows to control that the frequency values of the probe required for use are inside the useful bandwidth defined by the - 6 dB attenuation from the maximum amplitude response of the reference circuit versus frequency. Examples coming from measurements done among more than 200 probes, for which faults have been observed and replacements made by the manufacturer, are displayed and commented. (authors)

  16. Magnetoencephalography with a two-color pump probe atomic magnetometer.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Cort N.

    2010-07-01

    The authors have detected magnetic fields from the human brain with a compact, fiber-coupled rubidium spin-exchange-relaxation-free magnetometer. Optical pumping is performed on the D1 transition and Faraday rotation is measured on the D2 transition. The beams share an optical axis, with dichroic optics preparing beam polarizations appropriately. A sensitivity of <5 fT/{radical}Hz is achieved. Evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer. Recordings were validated by comparison with those taken by a commercial magnetoencephalography system. The design is amenable to arraying sensors around the head, providing a framework for noncryogenic, whole-head magnetoencephalography.

  17. Probing electronic and structural properties of single molecules on the atomic scale

    OpenAIRE

    Mohn, Fabian

    2012-01-01

    In this thesis work, a combination of low-temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM) was used to study single atoms and molecules on thin insulating films. We show that noncontact-AFM can yield important additional information for these systems, which had previously been studied only with STM. In particular, we demonstrate that the charge states of single gold adatoms can be detected with Kelvin probe force microscopy (KPFM). Furthermore, it is descr...

  18. Single-atom aided probe of the decoherence of a Bose-Einstein condensate

    OpenAIRE

    Ng, H. T.; Bose, S.

    2008-01-01

    We study a two-level atom coupled to a Bose-Einstein condensate. We show that the rules governing the decoherence of mesoscopic superpositions involving different classical-like states of the condensate can be probed using this system. This scheme is applicable irrespective of whether the condensate is initially in a coherent, thermal or more generally in any mixture of coherent states. The effects of atom loss and finite temperature to the decoherence can therefore be studied. We also discus...

  19. Probing non-Hermitian physics with flying atoms

    Science.gov (United States)

    Wen, Jianming; Xiao, Yanhong; Peng, Peng; Cao, Wanxia; Shen, Ce; Qu, Weizhi; Jiang, Liang

    2016-05-01

    Non-Hermtian optical systems with parity-time (PT) symmetry provide new means for light manipulation and control. To date, most of experimental demonstrations on PT symmetry rely on advanced nanotechnologies and sophisticated fabrication techniques to manmade solid-state materials. Here, we report the first experimental realization of optical anti-PT symmetry, a counterpart of conventional PT symmetry, in a warm atomic-vapor cell. By exploiting rapid coherence transport via flying atoms, we observe essential features of anti-PT symmetry with an unprecedented precision on phase-transition threshold. Moreover, our system allows nonlocal interference of two spatially-separated fields as well as anti-PT assisted four-wave mixing. Besides, another intriguing feature offered by the system is refractionless (or unit-refraction) light propagation. Our results thus represent a significant advance in non-Hermitian physics by bridging a firm connection with the AMO field, where novel phenomena and applications in quantum and nonlinear optics aided by (anti-)PT symmetry can be anticipated.

  20. Design and optimization of a harmonic probe with step cross section in multifrequency atomic force microscopy.

    Science.gov (United States)

    Cai, Jiandong; Wang, Michael Yu; Zhang, Li

    2015-12-01

    In multifrequency atomic force microscopy (AFM), probe's characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitude's sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement. PMID:26724066

  1. Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Klein

    2016-09-01

    Full Text Available Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

  2. Detecting and extracting clusters in atom probe data: A simple, automated method using Voronoi cells

    International Nuclear Information System (INIS)

    The analysis of the formation of clusters in solid solutions is one of the most common uses of atom probe tomography. Here, we present a method where we use the Voronoi tessellation of the solute atoms and its geometric dual, the Delaunay triangulation to test for spatial/chemical randomness of the solid solution as well as extracting the clusters themselves. We show how the parameters necessary for cluster extraction can be determined automatically, i.e. without user interaction, making it an ideal tool for the screening of datasets and the pre-filtering of structures for other spatial analysis techniques. Since the Voronoi volumes are closely related to atomic concentrations, the parameters resulting from this analysis can also be used for other concentration based methods such as iso-surfaces. - Highlights: • Cluster analysis of atom probe data can be significantly simplified by using the Voronoi cell volumes of the atomic distribution. • Concentration fields are defined on a single atomic basis using Voronoi cells. • All parameters for the analysis are determined by optimizing the separation probability of bulk atoms vs clustered atoms

  3. Detecting and extracting clusters in atom probe data: A simple, automated method using Voronoi cells

    Energy Technology Data Exchange (ETDEWEB)

    Felfer, P., E-mail: peter.felfer@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Ceguerra, A.V., E-mail: anna.ceguerra@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Ringer, S.P., E-mail: simon.ringer@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Cairney, J.M., E-mail: julie.cairney@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia)

    2015-03-15

    The analysis of the formation of clusters in solid solutions is one of the most common uses of atom probe tomography. Here, we present a method where we use the Voronoi tessellation of the solute atoms and its geometric dual, the Delaunay triangulation to test for spatial/chemical randomness of the solid solution as well as extracting the clusters themselves. We show how the parameters necessary for cluster extraction can be determined automatically, i.e. without user interaction, making it an ideal tool for the screening of datasets and the pre-filtering of structures for other spatial analysis techniques. Since the Voronoi volumes are closely related to atomic concentrations, the parameters resulting from this analysis can also be used for other concentration based methods such as iso-surfaces. - Highlights: • Cluster analysis of atom probe data can be significantly simplified by using the Voronoi cell volumes of the atomic distribution. • Concentration fields are defined on a single atomic basis using Voronoi cells. • All parameters for the analysis are determined by optimizing the separation probability of bulk atoms vs clustered atoms.

  4. Characterization of classical Gaussian processes using quantum probes

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, Claudia; Paris, Matteo G.A.

    2014-07-04

    We address the use of a single qubit as a quantum probe to characterize the properties of classical noise. In particular, we focus on the characterization of classical noise arising from the interaction with a stochastic field described by Gaussian processes. The tools of quantum estimation theory allow us to find the optimal state preparation for the probe, the optimal interaction time with the external noise, and the optimal measurement to effectively extract information on the noise parameter. We also perform a set of simulated experiments to assess the performances of maximum likelihood estimator, showing that the asymptotic regime, where the estimator is unbiased and efficient, is approximately achieved already after few thousands repeated measurements on the probe system. - Highlights: • Evaluation and optimization of QSNR for the estimation of the parameter g. • Assessment of the performances of MLE. • Discussion of the results.

  5. An atom probe field ion microscope investigation of the role of boron in precipitates and at grain boundaries in NiAl

    International Nuclear Information System (INIS)

    This paper reports that the high resolution analytical technique of Atom Probe Field Ion Microscopy (APFIM) has been used to characterize grain boundaries and the matrix of a stoichiometric NiAl alloy doped with 0.04 (100 wppm) and 0.12 at. % (300 wppm) boron. Field ion images revealed boron segregation to the grain boundaries. Atom probe elemental analysis of the grain boundaries measured a boron coverage of up to 30% of a monolayer. Extensive atom probe analyses also revealed a fine dispersion of nanoscale boride precipitates in the matrix. The boron segregation to the grain boundaries was found to correlate with the observed suppression of intergranular fracture. However, the decrease in ductility of boron-doped NiAl is attributed in part to the precipitation hardening effect of the boride phases

  6. Optical characterication of probes for photon scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    in a direct manner and has most often been inferred from the apparent quality of recorded optical images. Complicated near-field optical imaging characteristics, together with the possibility of topographically induced artefacts, however, has increased demands for a more reliable probe characterization...

  7. Atomic Carbon Is a Temperature Probe in Dark Clouds

    CERN Document Server

    Tatematsu, K; Plume, R; Evans, N J; Keene, J

    1999-01-01

    We have mapped the C I 3P1-3P0 line at 492 GHzin three molecular clouds immersed in weak ultraviolet radiation fields, TMC-1, L134N, and IC 5146. In all three clouds, the CI peak TA* ~ 1 K, with very small dispersion. The spatial C I distribution is extended and rather smooth. The J = 2-1 transitions of CO isotopomers were observed at the same angular resolution as C I. The C I peak TA* is typically a third of the peak TA* of 13CO J = 2-1, and the C I emission is usually more extended than emission in 13CO or C18O J=2-1. The C I linewidth is close to the 13CO J = 2-1 linewidth, larger than the C18O J = 2-1 line width, and smaller than the 12CO J = 2-1 linewidth. The uniformity of the C I peak TA* is remarkable for a line in the Wien portion of the Planck function and indicates a very uniform excitation temperature. This uniformity is best explained if the line if opaque and thermalized. If so, the CI line probes kinetic temperature in clouds exposed to low ultraviolet fluxes. This conclusion has significant i...

  8. Probing electronic state at atomic scale on the surface of SrVO3 film

    Science.gov (United States)

    Okada, Yoshinori; Shimizu, Ryota; Shiraki, Susumu; Hitosugi, Taro

    2014-03-01

    Probing electronic structure of atomically well controlled surface of Perovskite-type 3d transition-metal oxides have been attracting much interest because of their intriguing emergent physical properties by heterostructure engineering. In this study, we have especially focused on SrVO3, where importance of correlation effects has been considered. We successfully obtained atomically flat surfaces of SrVO3, which gave us the great opportunity to visualize correlated electronic state at atomic scale by means of spectroscopic imaging scanning tunneling spectroscopy. Based on the experimental data, we discuss spectroscopic signature of many body effects on the surface of SrVO3 system.

  9. High sensitivity probe absorption technique for time-of-flight measurements on cold atoms

    Indian Academy of Sciences (India)

    A K Mohapatra; C S Unnikrishnan

    2006-06-01

    We report on a phase-sensitive probe absorption technique with high sensitivity, capable of detecting a few hundred ultra-cold atoms in flight in an observation time of a few milliseconds. The large signal-to-noise ratio achieved is sufficient for reliable measurements on low intensity beams of cold atoms. We demonstrate the high sensitivity and figure of merit of the simple method by measuring the time-of-flight of atoms moving upwards from a magneto-optical trap released in the gravitational field.

  10. ATOM-PROBE RESULTS SUPPORT THE SKELETON MODEL FOR WC-Co

    OpenAIRE

    Henjered, A.; Hellsing, M.; Andrén, H.; Nordén, H.

    1984-01-01

    WC/WC boundaries in WC-Co type cemented carbides have been analysed with the atom-probe instrument. The boundaries contained about half a monolayer of cobalt (or Co + Cr) and can therefore be described as grain boundaries with cobalt segregation. The results support the "continuous skeleton" mode1 of WC-Co.

  11. Noncontact atomic force microscopy in liquid environment with quartz tuning fork and carbon nanotube probe

    DEFF Research Database (Denmark)

    Kageshima, M.; Jensenius, Henriette; Dienwiebel, M.;

    2002-01-01

    A force sensor for noncontact atomic force microscopy in liquid environment was developed by combining a multiwalled carbon nanotube (MWNT) probe with a quartz tuning fork. Solvation shells of octamethylcyclotetrasiloxane surface were detected both in the frequency shift and dissipation. Due...

  12. A variable-width harmonic probe for multifrequency atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jiandong; Zhang, Li [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT (Hong Kong); Xia, Qi, E-mail: qxia@mail.hust.edu.cn, E-mail: michael.wang@nus.edu.sg [State Key Laboratory of Digital Manufacturing Equipment of Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Luo, Yangjun [State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024 (China); Wang, Michael Yu, E-mail: qxia@mail.hust.edu.cn, E-mail: michael.wang@nus.edu.sg [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT (Hong Kong); Department of Mechanical Engineering, National University of Singapore, Singapore 117575 (Singapore)

    2015-02-16

    In multifrequency atomic force microscopy (AFM) to simultaneously measure topography and material properties of specimens, it is highly desirable that the higher order resonance frequencies of the cantilever probe are assigned to be integer harmonics of the excitation frequency. The harmonic resonances are essential for significant enhancement of the probe's response at the specified harmonic frequencies. In this letter, a structural optimization technique is employed to design cantilever probes so that the ratios between one or more higher order resonance frequencies and the fundamental natural frequency are ensured to be equal to specified integers and, in the meantime, that the fundamental natural frequency is maximized. Width profile of the cantilever probe is the design variable in optimization. Thereafter, the probes were prepared by modifying a commercial probe through the focused ion beam (FIB) milling. The resonance frequencies of the FIB fabricated probes were measured with an AFM. Results of the measurement show that the optimal design of probe is as effective as design prediction.

  13. Atomic structure and surface defects at mineral-water interfaces probed by in situ atomic force microscopy

    Science.gov (United States)

    Siretanu, Igor; van den Ende, Dirk; Mugele, Frieder

    2016-04-01

    Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all materials investigated, namely gibbsite, kaolinite, illite, and Na-montmorillonite of both natural and synthetic origin. Next to regions of perfect crystallinity, we routinely observe extended regions of various types of defects on the surfaces, including vacancies of one or few atoms, vacancy islands, atomic steps, apparently disordered regions, as well as strongly adsorbed seemingly organic and inorganic species. While their exact nature is frequently difficult to identify, our observations clearly highlight the ubiquity of such defects and their relevance for the overall physical and chemical properties of clay nanoparticle-water interfaces.Atomic scale details of surface structure play a crucial role for solid-liquid interfaces. While macroscopic characterization techniques provide averaged information about bulk and interfaces, high resolution real space imaging reveals unique insights into the role of defects that are believed to dominate many aspects of surface chemistry and physics. Here, we use high resolution dynamic Atomic Force Microscopy (AFM) to visualize and characterize in ambient water the morphology and atomic scale structure of a variety of nanoparticles of common clay minerals adsorbed to flat solid surfaces. Atomically resolved images of the (001) basal planes are obtained on all

  14. A FIM-atom probe investigation of the bainite transformation in CrMo steel

    International Nuclear Information System (INIS)

    To obtain a better understanding of the role played by Cr and Mo in the bainite transformation a Field-Ion Microscope - Atom Probe was constructed in order to study the distribution of the alloying elements near various types of boundaries on atomic scale. The distribution of alloying elements measured with this instrument is not so smooth on atomic scale as suggested by microprobe analysis. In a coherent twin boundary, formed during the bainite transformation, a depletion of the substitutionals Cr and Mo and an enhancement of the C content is observed, which is in accordance with the atomic model of a B.C.C. twin. In the twin plane the interstitial sites are even larger than the F.C.C. octahedral sites and this plane can act as an effective sink for the carbon atoms from bainitic ferrite. The depletion of Cr and Mo from the twin plane is due to interface coherency. (Auth.)

  15. Overcoming challenges in the study of nitrided microalloyed steels using atom probe

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Kelvin Y., E-mail: kelvin.xie@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Breen, Andrew J.; Yao, Lan; Moody, Michael P. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Gault, Baptiste [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Institute of Materials and Engineering Science, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia); Cairney, Julie M. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Ringer, Simon P., E-mail: simon.ringer@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

    2012-01-15

    Nitrided steels are widely used in the engineering field due to their superior hardness and other attractive properties. Atom probe tomography (APT) was employed to study two Nb-microalloyed CASTRIP steels with different N contents. A major challenge of using APT to study this group of materials is the presence of tails after Fe peaks in the mass spectra, which overestimates the composition for alloying elements such as Nb and Cu in the steels. One important factor that contributes to the tails is believed to be delayed field evaporation from Fe{sup 2+}. This artefact of the mass spectrum was observed to be the most severe when voltage pulsing was used. The application of laser pulses with energy ranging from 0.2 to 1.2 nJ successfully reduced the tails and lead to better compositional measurement accuracy. Spatial resolution in the z-direction (along the tip direction) was observed to be less affected by changing laser energy but deteriorates in x-y direction with increasing laser energy. This investigation suggests that pulsed-laser atom probe with {approx}0.4 nJ laser energy can be used to study this group of materials with improved mass resolution while still maintaining high spatial resolution. -- Highlights: Black-Right-Pointing-Pointer Degradation of mass resolution in the nitrided steel using voltage pulsed atom probe was identified. Black-Right-Pointing-Pointer The origin of the degradation was explored and considered to be associated with delayed evaporation. Black-Right-Pointing-Pointer The artifact caused by mass resolution degradation was successfully removed by the application of laser pulsed atom probe. Black-Right-Pointing-Pointer The effect of laser energy on mass resolution, composition measurement and spatial resolution was investigated. Black-Right-Pointing-Pointer Laser energy {approx}0.4 nJ was recommended to study this group of materials using laser pulsed atom probe.

  16. Overcoming challenges in the study of nitrided microalloyed steels using atom probe

    International Nuclear Information System (INIS)

    Nitrided steels are widely used in the engineering field due to their superior hardness and other attractive properties. Atom probe tomography (APT) was employed to study two Nb-microalloyed CASTRIP steels with different N contents. A major challenge of using APT to study this group of materials is the presence of tails after Fe peaks in the mass spectra, which overestimates the composition for alloying elements such as Nb and Cu in the steels. One important factor that contributes to the tails is believed to be delayed field evaporation from Fe2+. This artefact of the mass spectrum was observed to be the most severe when voltage pulsing was used. The application of laser pulses with energy ranging from 0.2 to 1.2 nJ successfully reduced the tails and lead to better compositional measurement accuracy. Spatial resolution in the z-direction (along the tip direction) was observed to be less affected by changing laser energy but deteriorates in x–y direction with increasing laser energy. This investigation suggests that pulsed-laser atom probe with ∼0.4 nJ laser energy can be used to study this group of materials with improved mass resolution while still maintaining high spatial resolution. -- Highlights: ► Degradation of mass resolution in the nitrided steel using voltage pulsed atom probe was identified. ► The origin of the degradation was explored and considered to be associated with delayed evaporation. ► The artifact caused by mass resolution degradation was successfully removed by the application of laser pulsed atom probe. ► The effect of laser energy on mass resolution, composition measurement and spatial resolution was investigated. ► Laser energy ∼0.4 nJ was recommended to study this group of materials using laser pulsed atom probe.

  17. Fusion boundary precipitation in thermally aged dissimilar metal welds studied by atom probe tomography and nanoindentation

    Science.gov (United States)

    Choi, Kyoung Joon; Kim, Taeho; Yoo, Seung Chang; Kim, Seunghyun; Lee, Jae Hyuk; Kim, Ji Hyun

    2016-04-01

    In this study, microstructural and mechanical characterizations were performed to investigate the effect of long-term thermal aging on the fusion boundary region between low-alloy steel and Nickel-based weld metal in dissimilar metal welds used in operating power plant systems. The effects of thermal aging treatment on the low-alloy steel side near the fusion boundary were an increase in the ratio of Cr constituents and Cr-rich precipitates and the formation and growth of Cr23C6. Cr concentrations were calculated using atom probe tomography. The accuracy of simulations of thermal aging effects of heat treatment was verified, and the activation energy for Cr diffusion in the fusion boundary region was calculated. The mechanical properties of fusion boundary region changed based on the distribution of Cr-rich precipitates, where the material initially hardened with the formation of Cr-rich precipitates and then softened because of the reduction of residual strain or coarsening of Cr-rich precipitates.

  18. Atom Probe Tomography Examination of Carbon Redistribution in Quenched and Tempered 4340 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Amy J. [Los Alamos National Laboratory; Miller, Michael K. [ORNL; Alexander, David J. [Los Alamos National Laboratory; Field, Robert D. [Los Alamos National Laboratory; Clarke, Kester D. [Los Alamos National Laboratory

    2012-08-07

    Quenching and tempering produces a wide range of mechanical properties in medium carbon, low alloyed steels - Study fragmentation behavior as a function of heat-treatment. Subtle microstructural changes accompany the mechanical property changes that result from quenching and tempering - Characterize the location and distribution of carbon and alloying elements in the microstructure using atom probe tomography (APT). Perform complementary transmission electron microscopy (TEM). Tempering influences the mechanical properties and fragmentation of quenched 4340 (hemi-shaped samples). APT revealed carbon-enriched features that contain a maximum of {approx}12-14 at.% carbon after quenching to RT (the level of carbon is perhaps associated with the extent of autotempering). TEM confirmed the presence of twinned martensite and indicates {var_epsilon} ({eta}) transition carbides after oil quenching to RT. Tempering at 325 C resulted in carbon-enriched plates (> 25 at.% C) with no significant element partitioning (transition carbides?). Tempering at 450 C and 575 C resulted in cementite ({approx} 25 at.% C) during late stage tempering; Cr, Mn, Mo partitioned to cementite and Si partitioned to ferrite. Tempering at 575 C resulted in P segregation at cementite interfaces and the formation of Cottrell atmospheres.

  19. Design and optimization of a harmonic probe with step cross section in multifrequency atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jiandong; Zhang, Li [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT (Hong Kong); Wang, Michael Yu, E-mail: michael.wang@nus.edu.sg [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT (Hong Kong); Department of Mechanical Engineering, National University of Singapore, Singapore 117575 (Singapore)

    2015-12-15

    In multifrequency atomic force microscopy (AFM), probe’s characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitude’s sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement.

  20. Design - manufacturing and characterization of specific ultrasonic probes

    International Nuclear Information System (INIS)

    Optimization of ultrasonic examinations requires essentially to determine precisely parameters used for manufacturing of probes and to check characteristics of beams used. The system presented permits an automatic determination of dimensions of beams in conditions which are totally representative of those of their use. In the field of ultrasonic examinations a good estimate or knowledge of sound beams is of great help to solve difficult examination problems. The FRAMATOME's Centre d'Etude et de Recherche en Essais Non Destructifs (CEREND) : (Study and Research Center in Non-Destructive Testing) has developed and elaborated various techniques in order to improve ultrasonic examinations with specific probes. These techniques concern design, manufacturing and characterization of these probes

  1. Spatial decomposition of molecular ions within 3D atom probe reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Breen, Andrew [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); Moody, Michael P. [Department of Materials, University of Oxford, Parks Road, OX13PH, Oxford (United Kingdom); Gault, Baptiste [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ont. L8S4L8 (Canada); Ceguerra, Anna V. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); Xie, Kelvin Y. [Johns Hopkins University, Department of Mechanical Engineering, Baltimore, MD 21218 (United States); Du, Sichao [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); School of Physics, The University of Sydney, NSW 2006 (Australia); Ringer, Simon P., E-mail: simon.ringer@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia)

    2013-09-15

    Two methods for separating the constituent atoms of molecular ions within atom probe tomography reconstructions are presented. The Gaussian Separation Method efficiently deconvolutes molecular ions containing two constituent atoms and is tested on simulated data before being applied to an experimental HSLA steel dataset containing NbN. The Delaunay Separation Method extends separation to larger complex ions and is also tested on simulated data before being applied to an experimental GaAs dataset containing many large (>3 atoms) complex ions. First nearest neighbour (1NN) distributions and images of the reconstruction before and after the separations are used to show the effect of the algorithms and their validity and practicality are also discussed. - Highlights: ► The need to deconvolute molecular ions within atom probe data is discussed. ► Two algorithms to separate the constituent atoms of molecular ions are proposed. ► The algorithms developed are tested on simulated and experimental data. ► Nearest neighbour distributions are used to highlight the improvements.

  2. Spatial decomposition of molecular ions within 3D atom probe reconstructions

    International Nuclear Information System (INIS)

    Two methods for separating the constituent atoms of molecular ions within atom probe tomography reconstructions are presented. The Gaussian Separation Method efficiently deconvolutes molecular ions containing two constituent atoms and is tested on simulated data before being applied to an experimental HSLA steel dataset containing NbN. The Delaunay Separation Method extends separation to larger complex ions and is also tested on simulated data before being applied to an experimental GaAs dataset containing many large (>3 atoms) complex ions. First nearest neighbour (1NN) distributions and images of the reconstruction before and after the separations are used to show the effect of the algorithms and their validity and practicality are also discussed. - Highlights: ► The need to deconvolute molecular ions within atom probe data is discussed. ► Two algorithms to separate the constituent atoms of molecular ions are proposed. ► The algorithms developed are tested on simulated and experimental data. ► Nearest neighbour distributions are used to highlight the improvements

  3. Atom probe tomography simulations and density functional theory calculations of bonding energies in Cu3Au

    KAUST Repository

    Boll, Torben

    2012-10-01

    In this article the Cu-Au binding energy in Cu3Au is determined by comparing experimental atom probe tomography (APT) results to simulations. The resulting bonding energy is supported by density functional theory calculations. The APT simulations are based on the Müller-Schottky equation, which is modified to include different atomic neighborhoods and their characteristic bonds. The local environment is considered up to the fifth next nearest neighbors. To compare the experimental with simulated APT data, the AtomVicinity algorithm, which provides statistical information about the positions of the neighboring atoms, is applied. The quality of this information is influenced by the field evaporation behavior of the different species, which is connected to the bonding energies. © Microscopy Society of America 2012.

  4. Spatial decomposition of molecular ions within 3D atom probe reconstructions.

    Science.gov (United States)

    Breen, Andrew; Moody, Michael P; Gault, Baptiste; Ceguerra, Anna V; Xie, Kelvin Y; Du, Sichao; Ringer, Simon P

    2013-09-01

    Two methods for separating the constituent atoms of molecular ions within atom probe tomography reconstructions are presented. The Gaussian Separation Method efficiently deconvolutes molecular ions containing two constituent atoms and is tested on simulated data before being applied to an experimental HSLA steel dataset containing NbN. The Delaunay Separation Method extends separation to larger complex ions and is also tested on simulated data before being applied to an experimental GaAs dataset containing many large (>3 atoms) complex ions. First nearest neighbour (1NN) distributions and images of the reconstruction before and after the separations are used to show the effect of the algorithms and their validity and practicality are also discussed. PMID:23522847

  5. A filtering method to reveal crystalline patterns from atom probe microscopy desorption maps.

    Science.gov (United States)

    Yao, Lan

    2016-01-01

    A filtering method to reveal the crystallographic information present in Atom Probe Microscopy (APM) data is presented. The method filters atoms based on the time difference between their evaporation and the evaporation of the previous atom. Since this time difference correlates with the location and the local structure of the evaporating atoms on the surface, it can be used to reveal any crystallographic information contained within APM data. The demonstration of this method is illustrated on: •A pure Al specimen for which crystallographic poles are clearly visible on the desorption patterns easily indexed.•Three Fe-15at.% Cr datasets where crystallographic patterns are less obvious and require this filtering method.

  6. ATOM PROBE FIM STUDY OF AN AMORPHOUS Pd-Si ALLOY

    OpenAIRE

    Yamamoto, M.; Yao, H; Nenno, S.; Ohnaka, I.; Fukusako, T.

    1987-01-01

    The amorphous structure of Pd84Si16 alloy wire obtained by inrotating-liquid spinning method from the liquid state, has been studied, in an atomic scale, by atom-probe field-ion microscopy. In the as-solidified specimen of Pd84Si16 alloy, whose electron diffraction pattern shows single halo ring, compositional fluctuation is found to exist in the range of 8 to 24 at% Si. The fluctuation is of the period of a few tenth nanometer, and it does not have long-range periodicity. We have discussed t...

  7. Electrical characterization of grain boundaries of CZTS thin films using conductive atomic force microscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Muhunthan, N.; Singh, Om Pal [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India); Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Singh, V.N., E-mail: singhvn@nplindia.org [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India)

    2015-10-15

    Graphical abstract: Experimental setup for conducting AFM (C-AFM). - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin film was grown by reactive co-sputtering. • The electronic properties were probed using conducting atomic force microscope, scanning Kelvin probe microscopy and scanning capacitance microscopy. • C-AFM current flow mainly through grain boundaries rather than grain interiors. • SKPM indicated higher potential along the GBs compared to grain interiors. • The SCM explains that charge separation takes place at the interface of grain and grain boundary. - Abstract: Electrical characterization of grain boundaries (GB) of Cu-deficient CZTS (Copper Zinc Tin Sulfide) thin films was done using atomic force microscopic (AFM) techniques like Conductive atomic force microscopy (CAFM), Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM). Absorbance spectroscopy was done for optical band gap calculations and Raman, XRD and EDS for structural and compositional characterization. Hall measurements were done for estimation of carrier mobility. CAFM and KPFM measurements showed that the currents flow mainly through grain boundaries (GB) rather than grain interiors. SCM results showed that charge separation mainly occurs at the interface of grain and grain boundaries and not all along the grain boundaries.

  8. Pulsed-laser atom probe studies of a precipitation hardened maraging TRIP steel.

    Science.gov (United States)

    Dmitrieva, O; Choi, P; Gerstl, S S A; Ponge, D; Raabe, D

    2011-05-01

    A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9 nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of the obtained cluster shapes to the TEM observations. No influence of laser pulse energy on chemical composition of the precipitates and on the chemical sharpness of their interfaces was detected.

  9. A computational geometry framework for the optimisation of atom probe reconstructions.

    Science.gov (United States)

    Felfer, Peter; Cairney, Julie

    2016-10-01

    In this paper, we present pathways for improving the reconstruction of atom probe data on a coarse (>10nm) scale, based on computational geometry. We introduce a way to iteratively improve an atom probe reconstruction by adjusting it, so that certain known shape criteria are fulfilled. This is achieved by creating an implicit approximation of the reconstruction through a barycentric coordinate transform. We demonstrate the application of these techniques to the compensation of trajectory aberrations and the iterative improvement of the reconstruction of a dataset containing a grain boundary. We also present a method for obtaining a hull of the dataset in both detector and reconstruction space. This maximises data utilisation, and can be used to compensate for ion trajectory aberrations caused by residual fields in the ion flight path through a 'master curve' and correct for overall shape deviations in the data.

  10. A computational geometry framework for the optimisation of atom probe reconstructions.

    Science.gov (United States)

    Felfer, Peter; Cairney, Julie

    2016-10-01

    In this paper, we present pathways for improving the reconstruction of atom probe data on a coarse (>10nm) scale, based on computational geometry. We introduce a way to iteratively improve an atom probe reconstruction by adjusting it, so that certain known shape criteria are fulfilled. This is achieved by creating an implicit approximation of the reconstruction through a barycentric coordinate transform. We demonstrate the application of these techniques to the compensation of trajectory aberrations and the iterative improvement of the reconstruction of a dataset containing a grain boundary. We also present a method for obtaining a hull of the dataset in both detector and reconstruction space. This maximises data utilisation, and can be used to compensate for ion trajectory aberrations caused by residual fields in the ion flight path through a 'master curve' and correct for overall shape deviations in the data. PMID:27449275

  11. Challenges in the study of Fe/MgO/Fe interfaces using 3D Atom Probe

    Energy Technology Data Exchange (ETDEWEB)

    Mazumder, B. [Groupe de Physique des Materiaux, UMR CNRS 6634, CORIA UMR CNRS 6614, UFR Sciences Site du Madrillet, Avenue de l' Université, B.P. 12 76801, Saint Etienne du Rouvray Cedex (France); Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Purohit, Viswas, E-mail: vishwas.purohit@gmail.com [Groupe de Physique des Materiaux, UMR CNRS 6634, CORIA UMR CNRS 6614, UFR Sciences Site du Madrillet, Avenue de l' Université, B.P. 12 76801, Saint Etienne du Rouvray Cedex (France); Department of Plasma Physics, Alliance College of Engineering and Design, Chikkahagade Cross, Chandapura, Anekal Main Road, Anekal, Bangalore 562106, Karnataka (India); Gruber, M.; Vella, A.; Vurpillot, F.; Deconihout, B. [Groupe de Physique des Materiaux, UMR CNRS 6634, CORIA UMR CNRS 6614, UFR Sciences Site du Madrillet, Avenue de l' Université, B.P. 12 76801, Saint Etienne du Rouvray Cedex (France)

    2015-08-31

    Detailed interface studies were conducted on two Fe/MgO/Fe systems having different thicknesses of MgO layers, using a laser assisted 3D atom probe. In conjunction with a detailed 3D reconstruction, the system exhibited an additional oxide formation at the interface between MgO and Fe of the multilayer structure. This oxide formation was found to be independent of the laser wavelength, laser fluence and the thickness of the intermediate layers. By using numerical simulations of field evaporation of two layers having two different evaporation fields, we discuss the possible oxidation mechanisms. - Highlights: • MgO layers (4, 32 nm) between Fe layers were analysed using a laser assisted atom probe. • Varying field evaporation voltages responsible for interfacial oxide layer (bottom) • Numerical simulation used to determine the phenomena taking place at the interfaces • Lasers of wavelengths 515 nm and 343 nm were used for this study.

  12. Phase decomposition and ordering in Ni-11.3 at.% Ti studied with atom probe tomography

    KAUST Repository

    Al-Kassab, Talaat

    2014-09-01

    The decomposition behavior of Ni-rich Ni-Ti was reassessed using Tomographic Atom Probe (TAP) and Laser Assisted Wide Angle Tomographic Atom Probe. Single crystalline specimens of Ni-11.3at.% Ti were investigated, the states selected from the decomposition path were the metastable γ″ and γ\\' states introduced on the basis of small-angle neutron scattering (SANS) and the two-phase model for evaluation. The composition values of the precipitates in these states could not be confirmed by APT data as the interface of the ordered precipitates may not be neglected. The present results rather suggest to apply a three-phase model for the interpretation of SANS measurements, in which the width of the interface remains nearly unchanged and the L12 structure close to 3:1 stoichiometry is maintained in the core of the precipitates from the γ″ to the γ\\' state. © 2014 Elsevier Ltd.

  13. Atom probe field ion microscopy and related topics: A bibliography 1989

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.K.; Hawkins, A.R.; Russell, K.F.

    1990-12-01

    This bibliography includes references related to the following topics: atom probe field ion microscopy (APFIM), field ion spectroscopy (FIM), field emission microscopy (FEM), liquid metal ion sources (LMIS), scanning tunneling microscopy (STM), and theory. Technique-orientated studies and applications are included. This bibliography covers the period 1989. The references contained in this document were compiled from a variety of sources including computer searches and personal lists of publications.

  14. Atom probe field-ion microscopy and related topics: A bibliography, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.K.; Hawkins, A.R.

    1989-10-01

    This bibliography includes references related to the following topics: field-ion microscopy (FIM), field emission microscopy (FEM), atom probe field-ion microscopy (APFIM), and liquid metal ion sources (LMIS). Technique-orientated studies and applications are included. The references contained in this document were compiled from a variety of sources including computer searches and personal lists of publications. To reduce the length of this document, the references have been reduced to the minimum necessary to locate the articles.

  15. Interface study of FeMgOFe magnetic tunnel junctions using 3D Atom Probe

    CERN Document Server

    Mazumder, B; Vella, A; Vurpillot, F; Deconihout, B

    2011-01-01

    A detailed interface study was conducted on a Fe/MgO/Fe system using laser assisted 3D atom probe. It exhibits an additional oxide formation at the second interface of the multilayer structure independent of laser wavelength, laser fluence and the thickness of the tunnel barrier. We have shown with the help of simulation that this phenomena is caused by the field evaporation of two layers having two different evaporation

  16. ATOM PROBE MICROANALYSIS OF WELD METAL IN A SUBMERGED ARC WELDED CHROMIUM-MOLYBDENUM STEEL

    OpenAIRE

    Josefsson, B.; Kvist, A.; Andrén, H.

    1987-01-01

    A submerged arc welded 2.25Cr - 1Mo steel has been investigated using electron microscopy and atom probe field ion microscopy. The bainitic microstructure of the as-welded steel consisted of ferrite and martensite. During heat treatment at 690°C the martensite transformed to ferrite and cementite and needle-shaped (Cr,Mo)2C carbides precipitated. Together with a substantial decrease in dislocation density, this resulted in an improvement of the toughness.

  17. Atom probe field-ion microscopy and related topics: A bibliography, 1988

    International Nuclear Information System (INIS)

    This bibliography includes references related to the following topics: field-ion microscopy (FIM), field emission microscopy (FEM), atom probe field-ion microscopy (APFIM), and liquid metal ion sources (LMIS). Technique-orientated studies and applications are included. The references contained in this document were compiled from a variety of sources including computer searches and personal lists of publications. To reduce the length of this document, the references have been reduced to the minimum necessary to locate the articles

  18. Pump-probe spectroscopy in degenerate two-level atoms with arbitrarily strong fields

    Science.gov (United States)

    Zigdon, T.; Wilson-Gordon, A. D.; Goren, C.; Rosenbluh, M.; Friedmann, H.

    2007-03-01

    We review our previous work on pump-probe spectroscopy in realistic degenerate two-level systems and model systems. In particular, we discuss the role of transfer of coherence (TOC) between the ground and excited hyperfine states in producing electromagnetically-induced transparency (EIA) peaks in the probe spectrum, when an F g goes to F e = F g +1 transition in an alkali-metal atom interacts with a strong pump and weak probe that have perpendicular polarizations. When the pump is rho + polarized and the probe pi polarized, this system can be modelled by an N system. We also discuss the role of transfer of population (TOP) between the Zeeman levels of the ground hyperfine state in producing EIA peaks when the pump and probe have the same polarization. This system can be modelled using a double two-level system. The role of Doppler broadening and phase-changing collisions in modifying the EIA-TOC and EIA-TOP absorption and refraction spectra is also discussed. All these spectra were calculated using MATLAB programs that both construct and solve the relevant Bloch equations. In our recent work, we consider the effect of a strong probe on the pump absorption and refraction spectra when the pump and probe polarizations are linear and perpendicular. It is difficult to solve this problem numerically due to the large number frequencies involved. In order to simplify the problem, we considered two cases: (i) rho + polarized pump and pi polarized probe, and (ii) rho + polarized pump and rho - polarized probe, and investigated a series of transitions in both Rb and Cs, using modified versions of the MATLAB programs devised for the weakprobe case. A number of interesting differences from the weak-probe case were found. For example, when the probe is sufficiently strong, we found the pump and probe spectra to show complementary behavior. In addition, as the number of Zeeman levels increase, the EIA peaks become progressively sharper, and are accompanied by steeper dispersion.

  19. Characterization of Cytokinetic Mutants Using Small Fluorescent Probes.

    Science.gov (United States)

    Smertenko, Andrei; Moschou, Panagiotis; Zhang, Laining; Fahy, Deirdre; Bozhkov, Peter

    2016-01-01

    Cytokinesis is a powerful paradigm for addressing fundamental questions of plant biology including molecular mechanisms of development, cell division, cell signaling, membrane trafficking, cell wall synthesis, and cytoskeletal dynamics. Genetics was instrumental in identification of proteins regulating cytokinesis. Characterization of mutant lines generated using forward or reverse genetics includes microscopic analysis for defects in cell division. Typically, failure of cytokinesis results in appearance of multinucleate cells, formation of cell wall stubs, and isotropic cell expansion in the root elongation zone. Small fluorescent probes served as a very effective tool for the detection of cytokinetic defects. Such probes stain living or formaldehyde-fixed specimens avoiding complex preparatory steps. Although resolution of the fluorescence probes is inferior to electron microscopy, the procedure is fast, easy, and does not require expensive materials or equipment. This chapter describes techniques for staining DNA with the probes DAPI and SYTO82, for staining membranes with FM4-64, and for staining cell wall with propidium iodide. PMID:26659964

  20. Resistance of single polyaniline fibers and their junctions measured by double-probe atomic force microscopy

    Science.gov (United States)

    Higuchi, Rintaro; Shingaya, Yoshitaka; Nakayama, Tomonobu

    2016-08-01

    Electrical properties of polyaniline (PANI) fibers are of our interest as a component of network materials. Using a multiple-probe atomic force microscope with tuning fork probes, we investigated the resistance of single PANI fibers and their cross-point junction where the fibers contact each other. The resistivity of single PANI fibers was measured to be on the order of 10 Ω cm, and the contact resistance between PANI fibers was on the order of GΩ. The resistances through single cross-point junctions between two PANI fibers were very much dependent on the experimental condition, that is, the cross-point junction is stabilized or destabilized by physically placing the probes onto the two fibers. This suggests the nanomechanical instability of the cross-point junctions and a possibility to construct strain-responsive PANI fiber networks.

  1. Influence of atomic force microscope (AFM) probe shape on adhesion force measured in humidity environment

    Institute of Scientific and Technical Information of China (English)

    阳丽; 涂育松; 谭惠丽

    2014-01-01

    In micro-manipulation, the adhesion force has very important influence on behaviors of micro-objects. Here, a theoretical study on the effects of humidity on the adhesion force is presented between atomic force microscope (AFM) tips and substrate. The analysis shows that the precise tip geometry plays a critical role on humidity depen-dence of the adhesion force, which is the dominant factor in manipulating micro-objects in AFM experiments. For a blunt (paraboloid) tip, the adhesion force versus humidity curves tends to the apparent contrast (peak-to-valley corrugation) with a broad range. This paper demonstrates that the abrupt change of the adhesion force has high correla-tion with probe curvatures, which is mediated by coordinates of solid-liquid-vapor contact lines (triple point) on the probe profiles. The study provides insights for further under-standing nanoscale adhesion forces and the way to choose probe shapes in manipulating micro-objects in AFM experiments.

  2. Pulsed-laser atom probe studies of a precipitation hardened maraging TRIP steel

    Energy Technology Data Exchange (ETDEWEB)

    Dmitrieva, O., E-mail: o.dmitrieva@mpie.de [Max-Planck-Institute for Iron Research, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Choi, P., E-mail: p.choi@mpie.de [Max-Planck-Institute for Iron Research, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Gerstl, S.S.A. [Imago Scientific Instruments, Madison, WI 53711 (United States); Ponge, D.; Raabe, D. [Max-Planck-Institute for Iron Research, Max-Planck-Str. 1, 40237 Duesseldorf (Germany)

    2011-05-15

    A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9 nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of the obtained cluster shapes to the TEM observations. No influence of laser pulse energy on chemical composition of the precipitates and on the chemical sharpness of their interfaces was detected. -- Research highlights: {yields} Changing the laser pulse energy in pulsed-laser atom probe could induce some changes in the analysis results of complex steels. {yields} Decreases in the evaporation fields and the ++/+ charge state ratios were detected with raising laser energy. {yields} Chemical composition of the intermetallic precipitates and the interface sharpness were not influenced by changing the laser energy.

  3. Atom probe tomography characterisation of a laser diode structure grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, Samantha E.; Humphreys, Colin J.; Oliver, Rachel A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Smeeton, Tim M.; Hooper, Stewart E.; Heffernan, Jonathan [Sharp Laboratories of Europe Limited, Edmund Halley Road, Oxford Science Park, Oxford, OX4 4GB (United Kingdom); Saxey, David W.; Smith, George D. W. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom)

    2012-03-01

    Atom probe tomography (APT) has been used to achieve three-dimensional characterization of a III-nitride laser diode (LD) structure grown by molecular beam epitaxy (MBE). Four APT data sets have been obtained, with fields of view up to 400 nm in depth and 120 nm in diameter. These data sets contain material from the InGaN quantum well (QW) active region, as well as the surrounding p- and n-doped waveguide and cladding layers, enabling comprehensive study of the structure and composition of the LD structure. Two regions of the same sample, with different average indium contents (18% and 16%) in the QW region, were studied. The APT data are shown to provide easy access to the p-type dopant levels, and the composition of a thin AlGaN barrier layer. Next, the distribution of indium within the InGaN QW was analyzed, to assess any possible inhomogeneity of the distribution of indium (''indium clustering''). No evidence for a statistically significant deviation from a random distribution was found, indicating that these MBE-grown InGaN QWs do not require indium clusters for carrier localization. However, the APT data show steps in the QW interfaces, leading to well-width fluctuations, which may act to localize carriers. Additionally, the unexpected presence of a small amount (x = 0.005) of indium in a layer grown intentionally as GaN was revealed. Finally, the same statistical method applied to the QW was used to show that the indium distribution within a thick InGaN waveguide layer in the n-doped region did not show any deviation from randomness.

  4. Atom-column distinction by Kikuchi pattern observed by an aberration-corrected convergent electron probe.

    Science.gov (United States)

    Saitoh, Koh; Tatara, Yoshihide; Tanaka, Nobuo

    2010-01-01

    Kikuchi patterns of an MgO crystal at the [110] incidence have been taken by a sub-angstrom electron beam focused on the single atom-column. A significant change in intensity has been observed in the 111 band; that is, the contrast in the central and side bands is reversed depending on the illuminated atom-column. The contrast reversal in the 111 band has been reproduced by multislice simulation using the frozen-phonon approach. The beam-position dependence of the 111 band intensity can be interpreted by electron channelling and the reciprocity theorem. The anomalous Kikuchi pattern can be a probe for identifying the illuminated atom-column, which is useful for column-by-column electron energy-loss spectroscopy and X-ray emission spectroscopy.

  5. Fiber Optic Dielectric Nanoparticles Characterization by Atom Probe Microscopy

    OpenAIRE

    Francois-Saint-Cyr, H; Martin, I.; Blanc, W; Lecoustumer, P; Hombourger, C; Neuville, D.; Larson, D. J.; Prosa, T.J.; Guillermier, C.

    2014-01-01

    The engineered processing of dielectric nanoparticles (DNPs) in optical fibers via luminescent ion-doping of silica-based glass aims at providing an enhanced spectroscopic behavior compared to pure silica. These DNPs should positively impact applications in high power fiber lasers, light sources with new wavelengths and telecommunications. The prevalence of large phase immiscibility domains in silicate systems containing divalent metal oxides (Mg for instance) promotes the formation of DNPs t...

  6. Large-Scale Fabrication of Carbon Nanotube Probe Tips For Atomic Force Microscopy Critical Dimension Imaging Applications

    Science.gov (United States)

    Ye, Qi Laura; Cassell, Alan M.; Stevens, Ramsey M.; Meyyappan, Meyya; Li, Jun; Han, Jie; Liu, Hongbing; Chao, Gordon

    2004-01-01

    Carbon nanotube (CNT) probe tips for atomic force microscopy (AFM) offer several advantages over Si/Si3N4 probe tips, including improved resolution, shape, and mechanical properties. This viewgraph presentation discusses these advantages, and the drawbacks of existing methods for fabricating CNT probe tips for AFM. The presentation introduces a bottom up wafer scale fabrication method for CNT probe tips which integrates catalyst nanopatterning and nanomaterials synthesis with traditional silicon cantilever microfabrication technology. This method makes mass production of CNT AFM probe tips feasible, and can be applied to the fabrication of other nanodevices with CNT elements.

  7. Characterization of an atomic hydrogen source for charge exchange experiments

    Science.gov (United States)

    Leutenegger, M. A.; Beiersdorfer, P.; Betancourt-Martinez, G. L.; Brown, G. V.; Hell, N.; Kelley, R. L.; Kilbourne, C. A.; Magee, E. W.; Porter, F. S.

    2016-11-01

    We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species.

  8. CHEMISORPTION OF CO AND METHANATION ON Rh SURFACES AT LOW TEMPERATURE AND LOW PRESSURE, AN ATOM-PROBE FIM STUDY

    OpenAIRE

    W. Liu; Ren, D.; Bao, C.; Tsong, T.

    1987-01-01

    Pulsed-laser imaging atom-probe and high resolution voltage pulsed atom-probe were employed to study the chemisorption behavior of CO on rhodium surfaces at low temperature and low pressure. The results are consistent and interesting. Our results support dissociative chemisorption on stepped surfaces of Rh and the effect of the surface structures. We also carried out methanation on Rh surfaces under adverse conditions and identified the intermediates of methanation with an isotope exchange te...

  9. Study of defects, radiation damage and implanted gases in solids by field-ion and atom-probe microscopy

    International Nuclear Information System (INIS)

    The ability of the field-ion microscope to image individual atoms has been applied, at Cornell University, to the study of fundamental properties of point defects in irradiated or quenched metals. The capability of the atom probe field-ion microscope to determine the chemistry - that is, the mass-to-charge ratio - of a single ion has been used to investigate the behavior of different implanted species in metals. A brief review is presented of: (1) the basic physical principles of the field-ion and atom-probe microscopes; (2) the many applications of these instruments to the study of defects and radiation damage in solids; and (3) the application of the atom-probe field-ion microscope to the study of the behavior of implanted 3He and 4He atoms in tungsten. The paper is heavily referenced so that the reader can pursue his specific research interests in detail

  10. Characterization of atom clusters in irradiated pressure vessel steels and model alloys

    International Nuclear Information System (INIS)

    In order to characterize the microstructural evolution of the iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions and, for comparison, low copper model alloys irradiated with neutrons and electrons have been studied. The characterization has been carried out mainly thanks to small angle neutron scattering and atom probe experiments. Both techniques lead to the conclusion that clusters develop with irradiations. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex. Solute atoms like Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs

  11. Orthogonal Supramolecular Polymer Formation on Highly Oriented Pyrolytic Graphite (HOPG) Surfaces Characterized by Scanning Probe Microscopy.

    Science.gov (United States)

    Gong, Yongxiang; Zhang, Siqi; Geng, Yanfang; Niu, Chunmei; Yin, Shouchun; Zeng, Qingdao; Li, Min

    2015-10-27

    Formation of an orthogonal supramolecular polymer on a highly oriented pyrolytic graphite (HOPG) surface was demonstrated for the first time by means of scanning probe microscopy (SPM). Atomic force microscopy (AFM) was employed to characterize the variation of both the thickness and the topography of the film formed from (1) monomer 1, (2) monomer 1/Zn(2+), and (3) monomer 1/Zn(2+)/cross-linker 2, respectively. Scanning tunneling microscopy (STM) was used to monitor the self-assembly behavior of monomer 1 itself, as well as 1/Zn(2+) ions binary system on graphite surface, further testifying for the formation of linear polymer via coordination interaction at the single molecule level. These results, given by the strong surface characterization tool of SPM, confirm the formation of the orthogonal polymer on the surface of graphite, which has great significance in regard to fabricating a complex superstructure on surfaces.

  12. Orthogonal Supramolecular Polymer Formation on Highly Oriented Pyrolytic Graphite (HOPG) Surfaces Characterized by Scanning Probe Microscopy.

    Science.gov (United States)

    Gong, Yongxiang; Zhang, Siqi; Geng, Yanfang; Niu, Chunmei; Yin, Shouchun; Zeng, Qingdao; Li, Min

    2015-10-27

    Formation of an orthogonal supramolecular polymer on a highly oriented pyrolytic graphite (HOPG) surface was demonstrated for the first time by means of scanning probe microscopy (SPM). Atomic force microscopy (AFM) was employed to characterize the variation of both the thickness and the topography of the film formed from (1) monomer 1, (2) monomer 1/Zn(2+), and (3) monomer 1/Zn(2+)/cross-linker 2, respectively. Scanning tunneling microscopy (STM) was used to monitor the self-assembly behavior of monomer 1 itself, as well as 1/Zn(2+) ions binary system on graphite surface, further testifying for the formation of linear polymer via coordination interaction at the single molecule level. These results, given by the strong surface characterization tool of SPM, confirm the formation of the orthogonal polymer on the surface of graphite, which has great significance in regard to fabricating a complex superstructure on surfaces. PMID:26457462

  13. EELS and atom probe tomography study of the evolution of the metal/oxide interface during zirconium alloy oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Gabory, Benoit de [Department of Mechanical and Nuclear Engineering, Penn State University, University Park, PA 16802 (United States); Dong, Yan, E-mail: yand@umich.edu [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Motta, Arthur T. [Department of Mechanical and Nuclear Engineering, Penn State University, University Park, PA 16802 (United States); Marquis, Emmanuelle A. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-07-15

    In an effort to understand the mechanisms resulting in the variations of corrosion rate observed throughout corrosion including at the first kinetic transition when the oxide temporarily loses its protective character, the oxide/metal interfaces of autoclave corroded Zircaloy-4 and ZIRLO™ before and after the transition are characterized using electron energy loss spectroscopy and atom probe tomography. The results reveal a complex structure of different phases at different stages of corrosion. The oxide/metal interface exhibits an intermediate layer, with an oxygen content between 45 and 55 O at.% and a suboxide layer corresponding to an oxygen-saturated solid solution in the metal matrix side (∼30 O at.%). Local variations are observed in the width of these characteristic structural features, especially near the transition. Good agreement on the layers present as well as their order, composition, and width was seen with the two techniques.

  14. Pump-probe spectroscopy of cold rubidium atoms in an integrating sphere

    Science.gov (United States)

    Wang, Wen-Li; Dong, Ri-Chang; Deng, Jian-Liao; Wang, Yu-Zhu

    2016-05-01

    Absorption spectra of cold rubidium atoms in an integrating sphere under the influence of a diffuse laser field have been systematically investigated. A pronounced dispersionlike structure centered at the light-shifted pump frequency is observed with a subnatural linewidth. In particular, two clearly resolved absorption resonances on the 5 S1 /2(F =2 ) →5 P3 /2(F'=3 ) transitions occur with variable probe beam intensity, which is consistent with our proposed theoretical model. Based on the two absorption resonances,we measure the dependence of light shifts, from which we can directly extract the effective Rabi frequency in a diffuse laser field, on the probe laser intensity, pump laser intensity, and pump laser detuning. Our work helps to identify the physical mechanisms behind these spectral features and is beneficial for studying the corresponding effect in a cold sample.

  15. Correlated ion analysis and the interpretation of atom probe mass spectra

    International Nuclear Information System (INIS)

    Several techniques are presented for extracting information from atom probe mass spectra by investigating correlations within multiple-ion detector events. Analyses of this kind can provide insights into the origins of noise, the shape of mass peaks, or unexpected anomalies within the spectrum. Data can often be recovered from within the spectrum noise by considering the time-of-flight differences between ions within a multiple event. Correlated ion detection, particularly when associated with shifts in ion energies, may be used to probe the phenomenon of molecular ion dissociation, including the questions of data loss due to ion pile-up or the generation of neutrals in the dissociation process. -- Research Highlights: → Multiple-ion detection events may contain information not seen in the mass spectrum. → Analysis of multiple events can yield information on molecular ion dissociation. → Neutral species may be generated by dissociation subsequent to field evaporation.

  16. Atom probe study of grain boundary segregation in technically pure molybdenum

    International Nuclear Information System (INIS)

    Molybdenum, a metal with excellent physical, chemical and high-temperature properties, is an interesting material for applications in lighting-technology, high performance electronics, high temperature furnace construction and coating technology. However, its applicability as a structural material is limited because of the poor oxidation resistance at high temperatures and a brittle-to-ductile transition around room temperature, which is influenced by the grain size and the content of interstitial impurities at the grain boundaries. Due to the progress of the powder metallurgical production during the last decades, the amount of impurities in the current quality of molybdenum has become so small that surface sensitive techniques are not applicable anymore. Therefore, the atom probe, which allows the detection of small amounts of impurities as well as their location, seems to be a more suitable technique. However, a site-specific specimen preparation procedure for grain boundaries in refractory metals with a dual focused ion beam/scanning electron microscope is still required. The present investigation describes the development and successful application of such a site-specific preparation technique for grain boundaries in molybdenum, which is significantly improved by a combination with transmission electron microscopy. This complimentary technique helps to improve the visibility of grain boundaries during the last preparation steps and to evidence the presence of grain and subgrain boundaries without segregants in atom probe specimens. Furthermore, in industrially processed and recrystallized molybdenum sheets grain boundary segregation of oxygen, nitrogen and potassium is successfully detected close to segregated regions which are believed to be former sinter pores. - Highlights: • First study of grain boundary segregation in molybdenum by atom probe • Site-specific preparation technique by FIB and TEM successfully developed • Grain boundary segregation of

  17. Probing Local Ionic Dynamics in Functional Oxides: From Nanometer to Atomic Scale

    Science.gov (United States)

    Kalinin, Sergei

    2014-03-01

    Vacancy-mediated electrochemical reactions in oxides underpin multiple applications ranging from electroresistive memories, to chemical sensors to energy conversion systems such as fuel cells. Understanding the functionality in these systems requires probing reversible (oxygen reduction/evolution reaction) and irreversible (cathode degradation and activation, formation of conductive filaments) electrochemical processes. In this talk, I summarize recent advances in probing and controlling these transformations locally on nanometer level using scanning probe microscopy. The localized tip concentrates the electric field in the nanometer scale volume of material, inducing local transition. Measured simultaneously electromechanical response (piezoresponse) or current (conductive AFM) provides the information on the bias-induced changes in material. Here, I illustrate how these methods can be extended to study local electrochemical transformations, including vacancy dynamics in oxides such as titanates, LaxSr1-xCoO3, BiFeO3, and YxZr1-xO2. The formation of electromechanical hysteresis loops and their bias-, temperature- and environment dependences provide insight into local electrochemical mechanisms. In materials such as lanthanum-strontium cobaltite, mapping both reversible vacancy motion and vacancy ordering and static deformation is possible, and can be corroborated by post mortem STEM/EELS studies. In ceria, a broad gamut of electrochemical behaviors is observed as a function of temperature and humidity. The possible strategies for elucidation ionic motion at the electroactive interfaces in oxides using high-resolution electron microscopy and combined ex-situ and in-situ STEM-SPM studies are discussed. In the second part of the talk, probing electrochemical phenomena on in-situ grown surfaces with atomic resolution is illustrated. I present an approach based on the multivariate statistical analysis of the coordination spheres of individual atoms to reveal

  18. Automated voxelization of 3D atom probe data through kernel density estimation.

    Science.gov (United States)

    Srinivasan, Srikant; Kaluskar, Kaustubh; Dumpala, Santoshrupa; Broderick, Scott; Rajan, Krishna

    2015-12-01

    Identifying nanoscale chemical features from atom probe tomography (APT) data routinely involves adjustment of voxel size as an input parameter, through visual supervision, making the final outcome user dependent, reliant on heuristic knowledge and potentially prone to error. This work utilizes Kernel density estimators to select an optimal voxel size in an unsupervised manner to perform feature selection, in particular targeting resolution of interfacial features and chemistries. The capability of this approach is demonstrated through analysis of the γ / γ' interface in a Ni-Al-Cr superalloy. PMID:25825028

  19. Opto-mechanical probe for combining atomic force microscopy and optical near-field surface analysis

    OpenAIRE

    Hoorn, van der, T.; Chavan, D.C.; B. Tiribilli; Margheri, G.; Mank, A.J.G.; Ariese, F.; Iannuzzi, D.

    2014-01-01

    We have developed a new easy-to-use probe that can be used to combine atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). We show that, using this device, the evanescent field, obtained by total internal reflection conditions in a prism, can be visualized by approaching the surface with the scanning tip. Furthermore, we were able to obtain simultaneous AFM and SNOM images of a standard test grating in air and in liquid. The lateral resolution in AFM and SNOM mode ...

  20. Momentum distributions of selected rare-gas atoms probed by intense femtosecond laser pulses

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2011-01-01

    We provide a direct comparison between numerical and experimental (Rudenko et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 L407) photoelectron momentum distributions in strong-field ionization of selected rare-gas atoms (He, Ne and Ar), probed by femtosecond linearly polarized laser pulses. The...... calculations are performed by solving the time-dependent Schrödinger equation within the single-active-electron approximation, and focal-volume effects are taken into account by appropriately averaging the results. The resulting momentum distributions are in quantitative agreement with the experimental...

  1. Initial study on Z-phase strengthened 9-12% Cr steels by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fang; Andren, Hans-Olof [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics

    2010-07-01

    The microstructure of two different types of Z-phase strengthened experimental steels, CrNbN-based or CrTaN-based, was investigated. Both steels underwent aging at 650 C for relatively short period of time, 24 hours or 1005 hours. Atom probe tomography was used to study the chemical composition of the matrix and precipitates, and the size and number density of the small precipitates. Both steels contain Laves phase at prior austenite grain boundaries and martensitic lath boundaries. The CrTaN-based steel was found more promising due to its finer and more densely distributed precipitates after 1005 hour aging. (orig.)

  2. Influence of supersaturated carbon on the diffusion of Ni in ferrite determined by atom probe tomography

    KAUST Repository

    Kresse, T.

    2013-09-01

    In patented and cold-drawn pearlitic steel wires dissociation of cementite occurs during mechanical deformation. In this study the influence of the carbon decomposition on the diffusion of nickel in ferrite is investigated by means of atom probe tomography. In the temperature range 423-523 K we observed a much smaller activation energy of Ni diffusion than for self-diffusion in body-centered cubic iron, indicating an increased vacancy density owing to enhanced formation of vacancy-carbon complexes. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Atom probe field ion microscopy and related topics: A bibliography 1993

    International Nuclear Information System (INIS)

    This bibliography, covering the period 1993, includes references related to the following topics: atom probe field ion microscopy (APFIM), field emission (FE), and field ion microscopy (FIM). Technique-oriented studies and applications are included. The references contained in this document were compiled from a variety of sources including computer searches and personal lists of publications. To reduce the length of this document, the references have been reduced to the minimum necessary to locate the articles. The references are listed alphabetically by authors, an Addendum of references missed in previous bibliographies is included

  4. Atom probe field ion microscopy and related topics: A bibliography 1990

    Energy Technology Data Exchange (ETDEWEB)

    Russell, K.F.; Miller, M.K.

    1991-12-01

    This bibliography includes references related to the following topics: atom probe field ion microscopy (APFIM), field ion microscopy (FIM), field emission (FE), ion sources, and field desorption mass microscopy (FDMM). Technique-orientated studies and applications are included. The bibliography covers the period 1990. The references contained in this document were compiled from a variety of sources including computer searches and personal lists of publications. To reduce the length of this document, the references have been reduced to the minimum necessary to locate the articles. The references, listed alphabetically by authors, are subdivided into the categories listed in paragraph one above. An Addendum of references missed in previous bibliographies is included.

  5. Shot noise as a probe of spin-polarized transport through single atoms

    DEFF Research Database (Denmark)

    Burtzlaff, Andreas; Weismann, Alexander; Brandbyge, Mads;

    2015-01-01

    Single atoms on Au(111) surfaces have been contacted with the Au tip of a low temperature scanning tunneling microscope. The shot noise of the current through these contacts has been measured up to frequencies of 120 kHz and Fano factors have been determined to characterize the transport channels...

  6. Atom probe, AFM, and STM studies on vacuum-fired stainless steels.

    Science.gov (United States)

    Stupnik, A; Frank, P; Leisch, M

    2009-04-01

    The surface morphology of grades 304L and 316LN stainless steels, after low-temperature bake-out process and vacuum annealing, has been studied by atomic force microscopy (AFM) and scanning tunnelling microscopy (STM). The local elemental composition on the surface before and after thermal treatment has been investigated by atom probe (AP) depth profiling measurements. After vacuum annealing, AFM and STM show significant changes in the surface structure and topology. Recrystallization and surface reconstruction is less pronounced on the 316LN stainless steel. AP depth profiling analyses result in noticeable nickel enrichment on the surface of grade 304L samples. Since hydrogen recombination is almost controlled by surface structure and composition, a strong influence on the outgassing behaviour by the particular surface microstructure can be deduced. PMID:19167824

  7. Probing atomic-scale friction on reconstructed surfaces of single-crystal semiconductors

    Science.gov (United States)

    Goryl, M.; Budzioch, J.; Krok, F.; Wojtaszek, M.; Kolmer, M.; Walczak, L.; Konior, J.; Gnecco, E.; Szymonski, M.

    2012-02-01

    Friction force microscopy (FFM) investigations have been performed on reconstructed (001) surfaces of InSb and Ge in an ultrahigh vacuum. On the c(8×2) reconstruction of InSb(001) atomic resolution is achieved under superlubric conditions, and the features observed in the lateral force images are precisely reproduced by numerical simulations, taking into account possible decorations of the probing tip. On the simultaneously acquired (1×3) reconstruction a significant disorder of the surface atoms is observed. If the loading force increases, friction becomes much larger on this reconstruction compared to the c(8×2) one. In FFM images acquired on the Ge(001)(2×1) characteristic substructures are resolved within the unit cells. In such a case, a strong dependence of the friction pattern on the scan direction is observed.

  8. Extracting features buried within high density atom probe point cloud data through simplicial homology.

    Science.gov (United States)

    Srinivasan, Srikant; Kaluskar, Kaustubh; Broderick, Scott; Rajan, Krishna

    2015-12-01

    Feature extraction from Atom Probe Tomography (APT) data is usually performed by repeatedly delineating iso-concentration surfaces of a chemical component of the sample material at different values of concentration threshold, until the user visually determines a satisfactory result in line with prior knowledge. However, this approach allows for important features, buried within the sample, to be visually obscured by the high density and volume (~10(7) atoms) of APT data. This work provides a data driven methodology to objectively determine the appropriate concentration threshold for classifying different phases, such as precipitates, by mapping the topology of the APT data set using a concept from algebraic topology termed persistent simplicial homology. A case study of Sc precipitates in an Al-Mg-Sc alloy is presented demonstrating the power of this technique to capture features, such as precise demarcation of Sc clusters and Al segregation at the cluster boundaries, not easily available by routine visual adjustment.

  9. Probing the nanoadhesion of Streptococcus sanguinis to titanium implant surfaces by atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Aguayo S

    2016-04-01

    Full Text Available Sebastian Aguayo,1 Nikolaos Donos,2 Dave Spratt,3 Laurent Bozec11Department of Biomaterials and Tissue Engineering, 2Periodontology Unit, 3Division of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UKAbstract: As titanium (Ti continues to be utilized in great extent for the fabrication of artificial implants, it is important to understand the crucial bacterium–Ti interaction occurring during the initial phases of biofilm formation. By employing a single-cell force spectroscopy technique, the nanoadhesive interactions between the early-colonizing Streptococcus sanguinis and a clinically analogous smooth Ti substrate were explored. Mean adhesion forces between S. sanguinis and Ti were found to be 0.32±0.00, 1.07±0.06, and 4.85±0.56 nN for 0, 1, and 60 seconds contact times, respectively; while adhesion work values were reported at 19.28±2.38, 104.60±7.02, and 1,317.26±197.69 aJ for 0, 1, and 60 seconds, respectively. At 60 seconds surface delays, minor-rupture events were modeled with the worm-like chain model yielding an average contour length of 668±12 nm. The mean force for S. sanguinis minor-detachment events was 1.84±0.64 nN, and Poisson analysis decoupled this value into a short-range force component of -1.60±0.34 nN and a long-range force component of -0.55±0.47 nN. Furthermore, a solution of 2 mg/mL chlorhexidine was found to increase adhesion between the bacterial probe and substrate. Overall, single-cell force spectroscopy of living S. sanguinis cells proved to be a reliable way to characterize early-bacterial adhesion onto machined Ti implant surfaces at the nanoscale.Keywords: atomic force microscopy, biophysics, bacterial adhesion, dental implants, titanium

  10. Atom probe tomography of secondary γ′ precipitation in a single crystal Ni-based superalloy after isothermal aging at 1100 °C

    Energy Technology Data Exchange (ETDEWEB)

    Tan, X.P., E-mail: xptan1985@gmail.com [IM 2NP, UMR 7334 CNRS, Université Aix-Marseille, 13397 Marseille Cedex 20 (France); Mangelinck, D.; Perrin-Pellegrino, C. [IM 2NP, UMR 7334 CNRS, Université Aix-Marseille, 13397 Marseille Cedex 20 (France); Rougier, L. [LSMX, MXG, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Gandin, Ch.-A. [CEMEF, UMR 7635 CNRS, MINES ParisTech, 06904 Sophia Antipolis (France); Jacot, A. [LSMX, MXG, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Ponsen, D.; Jaquet, V. [Snecma-SAFRAN Group, Service YQGC, 92702 Colombes (France)

    2014-10-25

    Highlights: • Bimodal size distribution of γ′ precipitates occurs after isothermal aging at 1100 °C. • Characterization of secondary γ′ by atom probe tomography. • It is proposed that the secondary γ′ occurs via a non-classical nucleation. • The coarsening of secondary γ′ precipitates well obeys the classical LSW theory. - Abstract: Secondary γ′ precipitation in a commercial single crystal Ni-based superalloy after the 1100 °C isothermal aging has been investigated by atom probe tomography. After the isothermal aging for 300 s, 1800 s and 3600 s, a bimodal size distribution of larger primary γ′ precipitates and numerous smaller secondary γ′ precipitates was obtained. It is proposed that the secondary γ′ precipitated via a non-classical nucleation mode. The coarsening of secondary γ′ precipitates well obeys the classical LSW theory.

  11. Attosecond probing of state-resolved ionization and superpositions of atoms and molecules

    Science.gov (United States)

    Leone, Stephen

    2016-05-01

    Isolated attosecond pulses in the extreme ultraviolet are used to probe strong field ionization and to initiate electronic and vibrational superpositions in atoms and small molecules. Few-cycle 800 nm pulses produce strong-field ionization of Xe atoms, and the attosecond probe is used to measure the risetimes of the two spin orbit states of the ion on the 4d inner shell transitions to the 5p vacancies in the valence shell. Step-like features in the risetimes due to the subcycles of the 800 nm pulse are observed and compared with theory to elucidate the instantaneous and effective hole dynamics. Isolated attosecond pulses create massive superpositions of electronic states in Ar and nitrogen as well as vibrational superpositions among electronic states in nitrogen. An 800 nm pulse manipulates the superpositions, and specific subcycle interferences, level shifting, and quantum beats are imprinted onto the attosecond pulse as a function of time delay. Detailed outcomes are compared to theory for measurements of time-dynamic superpositions by attosecond transient absorption. Supported by DOE, NSF, ARO, AFOSR, and DARPA.

  12. The study of quantitativeness in atom probe analysis of alloying elements in steel

    International Nuclear Information System (INIS)

    The quantitativeness in atom probe analysis of dilute solute alloying elements in steel was systematically investigated. The samples of binary Fe-Si, Fe-Ti, Fe-Cr, Fe-Cu, Fe-Mn and Fe-Mo alloys were prepared for present study. The apparent compositions of alloying elements were examined by three-dimensional atom probe (3DAP) under various experimental conditions. The temperature dependence of the apparent compositions varied largely with the alloys, which indicated that the degree of preferential evaporation or retention varied with the alloying elements. Furthermore, the analysis direction dependence of the apparent Mn composition was examined in the Fe-Mn alloy. The experimental results indicated that the order of the field evaporation rate of elements in steel was Cu>Cr>Mn∼Mo>Fe>Ti∼Si. The field evaporability of alloying elements in steel was discussed in terms of the solution enthalpy of the alloying elements and the phase types of the binary Fe alloys.

  13. Laser-assisted atom probe tomography investigation of magnetic FePt nanoclusters: First experiments

    Energy Technology Data Exchange (ETDEWEB)

    Folcke, E.; Larde, R. [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, 76801 Saint Etienne du Rouvray (France); Le Breton, J.M., E-mail: jean-marie.lebreton@univ-rouen.fr [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, 76801 Saint Etienne du Rouvray (France); Gruber, M.; Vurpillot, F. [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, 76801 Saint Etienne du Rouvray (France); Shield, J.E.; Rui, X. [Department of Mechanical and Materials Engineering, Nebraska Center for Materials and Nanoscience, University of Nebraska, N104 WSEC, Lincoln, NE 68588 (United States); Patterson, M.M. [Department of Physics, University of Wisconsin-Stout, Menomonie, WI 54751 (United States)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer FePt nanoclusters dispersed in a Cr matrix were studied by atom probe tomography. Black-Right-Pointing-Pointer Simulated experiments were conducted to study the artefacts of the analysis. Black-Right-Pointing-Pointer In FePt nanoclusters, Fe and Pt are present in equiatomic proportions. Black-Right-Pointing-Pointer FePt nanoclusters are homogeneous, no core-shell structure is observed. - Abstract: FePt nanoclusters dispersed in a Cr matrix have been investigated by laser-assisted atom probe tomography. The results were analysed according to simulated evaporation experiments. Three-dimensional (3D) reconstructions reveal the presence of nanoclusters roughly spherical in shape, with a size in good agreement with previous transmission electron microscopy observations. Some clusters appear to be broken up after the evaporation process due to the fact that the Cr matrix has a lower evaporation field than Fe and Pt. It is thus shown that the observed FePt nanoclusters are chemically homogeneous. They contain Fe and Pt in equiatomic proportions, with no core-shell structure observed.

  14. Fabrication of a polymer-metal combined atomic force microscopy probe for coarse food surface imaging.

    Science.gov (United States)

    Kang, Hyen-Wook; Muramatsu, Hiroshi; Kwon, Young-Soo

    2013-05-01

    We fabricated a polymer-metal combined atomic force microscopy (AFM) probe by two steps; a polymeric resin was used at first step, and a metal-ion was used at second step which needs more fabricating time than the resin. At first step, we fabricated a cylindrical base on to a commercial cantilever. At second step, we fabricated a conical probe on to the fabricated cylindrical base. To make the conical probe composed with silver, a 0.2 M aqueous solution of silver nitrate (AgNO3) was used. A 50 microm length polymeric-metallic hybrid tip has been fabricated to observe large bio and food samples. Generally, the AFM images of bio/food samples show cliff-like sharp patters in vertical. However, the AFM image by fabricated long tip shows clear structure of each brown rice flours. As most of commercial tips have three-angular pyramidal, the scanned results should be influenced by the lateral face of the three-angular pyramid, which results in cliff-like images. Because the sample size is large, the side area of the sample was adversely affected by the pyramidal structure during imaging. This problem may be resolved by designing conical structure tips. As the conical structure has no edge, the AFM image becomes clear. The fabricated tip has conical structure, and a clear AFM image was achieved. PMID:23858900

  15. Indium clustering in a-plane InGaN quantum wells as evidenced by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Fengzai; Zhu, Tongtong; Oehler, Fabrice; Fu, Wai Yuen; Griffiths, James T.; Massabuau, Fabien C.-P.; Kappers, Menno J.; Oliver, Rachel A., E-mail: rao28@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Martin, Tomas L.; Bagot, Paul A. J.; Moody, Michael P., E-mail: michael.moody@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2015-02-16

    Atom probe tomography (APT) has been used to characterize the distribution of In atoms within non-polar a-plane InGaN quantum wells (QWs) grown on a GaN pseudo-substrate produced using epitaxial lateral overgrowth. Application of the focused ion beam microscope enabled APT needles to be prepared from the low defect density regions of the grown sample. A complementary analysis was also undertaken on QWs having comparable In contents grown on polar c-plane sample pseudo-substrates. Both frequency distribution and modified nearest neighbor analyses indicate a statistically non-randomized In distribution in the a-plane QWs, but a random distribution in the c-plane QWs. This work not only provides insights into the structure of non-polar a-plane QWs but also shows that APT is capable of detecting as-grown nanoscale clustering in InGaN and thus validates the reliability of earlier APT analyses of the In distribution in c-plane InGaN QWs which show no such clustering.

  16. Analysis of medical device materials with the local electrode atom probe

    International Nuclear Information System (INIS)

    Full text: As medical technology advances towards microsurgical and minimally invasive techniques, there is a drive to produce ever-smaller devices that demand higher material performance and hence enhanced nano and micro-scale control of material structure. These devices are made from stainless steel alloys, Nitinol, titanium, CoCrMo, and non-metals such as pyrolytic carbon and silicon. These applications are made possible due to suitable physical and mechanical properties, good corrosion resistance in biological environments, reasonable biocompatibility, and good manufacturability. With respect to the metals, the nano-structure and composition of the material surface, typically an oxide, is especially critical since biological responses and corrosion occur at the material-environment interface. Thus, there is an increasing need to understand the 3-D structure and composition of metallic biomaterials at the atomic scale. Three-dimensional atom probe microscopy can uniquely provide such atomic-level structural information. In the present study several of these medical device materials were examined. These include a 316L stainless steel alloy which is widely used in implanted spinal fixation devices, bone screws, cardiovascular and neurological stents, a cast CoCrMo acetabular hip cup of a Cormet metal-on-metal Hip Resurfacing System (Corin Group, Cirencester, England) that was rejected for clinical use, Nitinol wires specimens such as are used for stents and guide wires, and low temperature pyrolytic carbon as used in clinical heart valve prosthetics. (author)

  17. Studying nearest neighbor correlations by atom probe tomography (APT) in metallic glasses as exemplified for Fe40Ni40B20 glassy ribbons

    KAUST Repository

    Shariq, Ahmed

    2012-01-01

    A next nearest neighbor evaluation procedure of atom probe tomography data provides distributions of the distances between atoms. The width of these distributions for metallic glasses studied so far is a few Angstrom reflecting the spatial resolution of the analytical technique. However, fitting Gaussian distributions to the distribution of atomic distances yields average distances with statistical uncertainties of 2 to 3 hundredth of an Angstrom. Fe 40Ni40B20 metallic glass ribbons are characterized this way in the as quenched state and for a state heat treated at 350 °C for 1 h revealing a change in the structure on the sub-nanometer scale. By applying the statistical tool of the χ2 test a slight deviation from a random distribution of B-atoms in the as quenched sample is perceived, whereas a pronounced elemental inhomogeneity of boron is detected for the annealed state. In addition, the distance distribution of the first fifteen atomic neighbors is determined by using this algorithm for both annealed and as quenched states. The next neighbor evaluation algorithm evinces a steric periodicity of the atoms when the next neighbor distances are normalized by the first next neighbor distance. A comparison of the nearest neighbor atomic distribution for as quenched and annealed state shows accumulation of Ni and B. Moreover, it also reveals the tendency of Fe and B to move slightly away from each other, an incipient step to Ni rich boride formation. © 2011 Elsevier B.V.

  18. Characterization of Antisticking Layers for UV Nanoimprint Lithography Molds with Scanning Probe Microscopy

    Science.gov (United States)

    Masaaki Kurihara,; Sho Hatakeyama,; Noriko Yamada,; Takeya Shimomura,; Takaharu Nagai,; Kouji Yoshida,; Tatsuya Tomita,; Morihisa Hoga,; Naoya Hayashi,; Hiroyuki Ohtani,; Masamichi Fujihira,

    2010-06-01

    Antisticking layers (ASLs) on UV nanoimprint lithography (UV-NIL) molds were characterized by scanning probe microscopies (SPMs) in addition to macroscopic analyses of work of adhesion and separation force. Local physical properties of the ASLs were measured by atomic force microscopy (AFM) and friction force microscopy (FFM). The behavior of local adhesive forces measured with AFM on several surfaces was consistent with that of work of adhesion obtained from contact angle. The ASLs were coated by two different processes, i.e., one is a vapor-phase process and the other a spin-coating process. The homogeneity of the ASLs prepared by the vapor-phase process was better than that of those prepared by the spin-coating process. In addition, we measured the thicknesses of ASL patterns prepared by a lift-off method to investigate the effect of the ASL thicknesses on critical dimensions of the molds with ASLs and found that this effect is not negligible.

  19. Characterizing Surfaces of the Wide Bandgap Semiconductor Ilmenite with Scanning Probe Microcopies

    Science.gov (United States)

    Wilkins, R.; Powell, Kirk St. A.

    1997-01-01

    Ilmenite (FeTiO3) is a wide bandgap semiconductor with an energy gap of about 2.5eV. Initial radiation studies indicate that ilmenite has properties suited for radiation tolerant applications, as well as a variety of other electronic applications. Two scanning probe microscopy methods have been used to characterize the surface of samples taken from Czochralski grown single crystals. The two methods, atomic force microscopy (AFM) and scanning tunneling microscopy (STM), are based on different physical principles and therefore provide different information about the samples. AFM provides a direct, three-dimensional image of the surface of the samples, while STM give a convolution of topographic and electronic properties of the surface. We will discuss the differences between the methods and present preliminary data of each method for ilmenite samples.

  20. Physicochemical and Atomic Characterization of Silver Powder after Biofield Treatment

    OpenAIRE

    Trivedi, Mahendra Kumar

    2015-01-01

    Silver is widely utilized as antimicrobial agent and wound dressing, where its shape, size, surface area, and surface charge play an important role. The aim of present study was to evaluate the impact of biofield treatment on physicochemical and atomic properties of silver powder. The silver powder was divided into two groups, coded as control and treatment. The treatment group received Mr. Trivedi’s biofield treatment. Subsequently, control and treated samples were characterized using ...

  1. Shape-dependent adhesion and friction of Au nanoparticles probed with atomic force microscopy

    International Nuclear Information System (INIS)

    The relation between surface structure and friction and adhesion is a long-standing question in tribology. Tuning the surface structure of the exposed facets of metal nanoparticles is enabled by shape control. We investigated the effect of the shape of Au nanoparticles on friction and adhesion. Two nanoparticle systems, cubic nanoparticles with a low-index (100) surface and hexoctahedral nanoparticles with a high-index (321) surface, were used as model nanoparticle surfaces. Atomic force microscopy was used to probe the nanoscale friction and adhesion on the nanoparticle surface. Before removing the capping layers, the friction results include contributions from both the geometric factor and the presence of capping layers. After removing the capping layers, we can see the exclusive effect of the surface atomic structure while the geometric effect is maintained. We found that after removing the capping layer, the cubic Au nanoparticles exhibited higher adhesion and friction, compared with cubes capped with layers covering 25% and 70%, respectively. On the other hand, the adhesion and friction of hexoctahedral Au nanoparticles decreased after removing the capping layers, compared with nanoparticles with capping layers. The difference in adhesion and friction forces between the bare Au surfaces and Au nanoparticles with capping layers cannot be explained by geometric factors, such as the slope of the nanoparticle surfaces. The higher adhesion and friction forces on cubic nanoparticles after removing the capping layers is associated with the atomic structure of (100) and (321) (i.e., the flat (100) surfaces of the cubic nanoparticles have a larger contact area, compared with the rough (321) surfaces of the hexoctahedral nanoparticles). This study implies an intrinsic relation between atomic structure and nanomechanical properties, with potential applications for controlling nanoscale friction and adhesion via colloid chemistry. (paper)

  2. Detection of slow atoms confined in a Cesium vapor cell by spatially separated pump and probe laser beams

    CERN Document Server

    Todorov, Petko; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel

    2013-01-01

    The velocity distribution of atoms in a thermal gas is usually described through a Maxwell-Boltzman distribution of energy, and assumes isotropy. As a consequence, the probability for an atom to leave the surface under an azimuth angle {\\theta} should evolve as cos {\\theta}, in spite of the fact that there is no microscopic basis to justify such a law. The contribution of atoms moving at a grazing incidence towards or from the surface, i.e. atoms with a small normal velocity, here called "slow" atoms, reveals essential in the development of spectroscopic methods probing a dilute atomic vapor in the vicinity of a surface, enabling a sub-Doppler resolution under a normal incidence irradiation. The probability for such "slow" atoms may be reduced by surface roughness and atom-surface interaction. Here, we describe a method to observe and to count these slow atoms relying on a mechanical discrimination, through spatially separated pump and probe beams. We also report on our experimental progresses toward such a g...

  3. Gentle and fast atomic force microscopy with a piezoelectric scanning probe for nanorobotics applications

    International Nuclear Information System (INIS)

    A novel dual tip nanomanipulation atomic force microscope (AFM) platform operating in ambient conditions is presented. The system is equipped with a high frequency quartz piezoelectric self-sensing scanning probe for fast imaging and a passive cantilever for manipulation. The system is validated by imaging and selective pushing/pulling of gold colloid beads (diameters from 80 to 180 nm). This provides a more compact integration compared to an external optical lever and avoids several of its drawbacks such as optical interference and noise, and recalibration in the case of a moving cantilever and a fixed laser source and photodiode sensor. Moreover, as the quartz oscillator exhibits oscillation amplitudes in the sub-picometer range with a resonant frequency in the megahertz range, this dynamic force sensor is ideal for fast AFM imaging. Experiments show an increase by five times in imaging speed compared to a classical AFM system. (paper)

  4. Probing dark energy with an atom interferometer in an optical cavity

    Science.gov (United States)

    Jaffe, Matthew; Haslinger, Philipp; Hamilton, Paul; Mueller, Holger; Khoury, Justin; Elder, Benjamin

    2016-05-01

    If dark energy -- which drives the accelerated expansion of the universe -- consists of a light scalar field, it might be detectable as a ``fifth force'' between normal-matter objects, in potential conflict with precision tests of gravity. Chameleon fields and other theories with screening mechanisms can evade such tests by suppressing this force in regions of high density, such as the laboratory. Our experiments constrain these dark energy models using atoms in an ultrahigh-vacuum chamber as probes to expose the screened fields. Using a cesium matter wave interferometer in an optical cavity, we set stringent bounds on coupling screened theories to matter. A further 4 to 5 orders of magnitude would completely rule out chameleon and f(R) theories. I will describe this first tabletop dark energy search, and present the hundredfold boost in sensitivity we have since achieved.

  5. Simulating compact quantum electrodynamics with ultracold atoms: probing confinement and nonperturbative effects.

    Science.gov (United States)

    Zohar, Erez; Cirac, J Ignacio; Reznik, Benni

    2012-09-21

    Recently, there has been much interest in simulating quantum field theory effects of matter and gauge fields. In a recent work, a method for simulating compact quantum electrodynamics (CQED) using Bose-Einstein condensates has been suggested. We suggest an alternative approach, which relies on single atoms in an optical lattice, carrying 2l + 1 internal levels, which converges rapidly to CQED as l increases. That enables the simulation of CQED in 2 + 1 dimensions in both the weak and the strong coupling regimes, hence, allowing us to probe confinement as well as other nonperturbative effects of the theory. We provide an explicit construction for the case l = 1 which is sufficient for simulating the effect of confinement between two external static charges.

  6. Graphene Coatings: Probing the Limits of the One Atom Thick Protection Layer

    DEFF Research Database (Denmark)

    Nilsson, Louis; Andersen, Mie; Balog, Richard;

    2012-01-01

    The limitations of graphene as an effective corrosion-inhibiting coating on metal surfaces, here exemplified by the hex-reconstructed Pt(100) surface, are probed by scanning tunneling microscopy measurements and density functional theory calculations. While exposure of small molecules directly onto...... the Pt(100) surface will lift the reconstruction, a single graphene layer is observed to act as an effective coating, protecting the reactive surface from O2 exposure and thus preserving the reconstruction underneath the graphene layer in O2 pressures as high as 104 mbar. A similar protective effect...... against CO is observed at CO pressures below 106 mbar. However, at higher pressures CO is observed to intercalate under the graphene coating layer, thus lifting the reconstruction. The limitations of the coating effect are further tested by exposure to hot atomic hydrogen. While the coating can withstand...

  7. Evaporation mechanisms of MgO in laser assisted atom probe tomography

    KAUST Repository

    Mazumder, Baishakhi

    2011-05-01

    In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

  8. Analysis of deuterium in V-Fe5at.% film by atom probe tomography (APT)

    KAUST Repository

    Gemma, Ryota

    2011-09-01

    V-Fe5at.% 2 and 10-nm thick single layered films were prepared by ion beam sputtering on W substrate. They were loaded with D from gas phase at 0.2 Pa and at 1 Pa, respectively. Both lateral and depth D distribution of these films was investigated in detail by atom probe tomography. The results of analysis are in good agreement between the average deuterium concentration and the value, expected from electromotive force measurement on a similar flat film. An enrichment of deuterium at the V/W interface was observed for both films. The origin of this D-accumulation was discussed in respect to electron transfer, mechanical stress and misfit dislocations. © 2010 Elsevier B.V. All rights reserved.

  9. Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography.

    Science.gov (United States)

    Meher, S; Rojhirunsakool, T; Nandwana, P; Tiley, J; Banerjee, R

    2015-12-01

    The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

  10. Understanding Atom Probe Tomography of Oxide-Supported Metal Nanoparticles by Correlation with Atomic-Resolution Electron Microscopy and Field Evaporation Simulation.

    Science.gov (United States)

    Devaraj, Arun; Colby, Robert; Vurpillot, François; Thevuthasan, Suntharampillai

    2014-04-17

    Oxide-supported metal nanoparticles are widely used in heterogeneous catalysis. The increasingly detailed design of such catalysts necessitates three-dimensional characterization with high spatial resolution and elemental selectivity. Laser-assisted atom probe tomography (APT) is uniquely suited to the task but faces challenges with the evaporation of metal/insulator systems. Correlation of APT with aberration-corrected scanning transmission electron microscopy (STEM), for Au nanoparticles embedded in MgO, reveals preferential evaporation of the MgO and an inaccurate assessment of nanoparticle composition. Finite element field evaporation modeling is used to illustrate the evolution of the evaporation front. Nanoparticle composition is most accurately predicted when the MgO is treated as having a locally variable evaporation field, indicating the importance of considering laser-oxide interactions and the evaporation of various molecular oxide ions. These results demonstrate the viability of APT for analysis of oxide-supported metal nanoparticles, highlighting the need for developing a theoretical framework for the evaporation of heterogeneous materials.

  11. The probe gain with and without inversion in a four-level atomic model: light amplification at a short wavelength

    Institute of Scientific and Technical Information of China (English)

    吴金辉; 王登攀; 张惠芳; 肖志宏; 高锦岳

    2003-01-01

    We propose a new four-level atomic model for achieving light amplification at a short wavelength, where direct incoherent pumping into the top level is avoided by the advantage of coherent pumping. In this model, the lower level of the probe transition is an excited state but not the usual ground state. By analytical as well as numerical calculations, we find that the probe gain, either with or without population inversion, which depends on the relation between spontaneous decay rates γ42 and γ21, can be achieved with proper parameters. We note that the Raman scattering gain always plays an important role in achieving the probe amplification.

  12. Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

    Science.gov (United States)

    Piazolo, Sandra; La Fontaine, Alexandre; Trimby, Patrick; Harley, Simon; Yang, Limei; Armstrong, Richard; Cairney, Julie M.

    2016-02-01

    Trace elements diffuse negligible distances through the pristine crystal lattice in minerals: this is a fundamental assumption when using them to decipher geological processes. For example, the reliable use of the mineral zircon (ZrSiO4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility. Here, using atom probe tomography, we document the effects of crystal-plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility. Dislocations that move through the lattice accumulate U and other trace elements. Pipe diffusion along dislocation arrays connected to a chemical or structural sink results in continuous removal of selected elements (for example, Pb), even after deformation has ceased. However, in disconnected dislocations, trace elements remain locked. Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials.

  13. Growth rate model and doping metrology by atom probe tomography in silicon nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.H.; Larde, R.; Cadel, E.; Pareige, P. [Groupe de Physique des Materiaux, Universite et INSA de Rouen, UMR CNRS 6634, Av. de l' Universite, BP 12, 76801 Saint Etienne du Rouvray (France); Xu, T.; Grandidier, B.; Nys, J.P.; Stievenard, D. [Institut d' Electronique, de Microelectronique et de Nanotechnologie, UMR CNRS 8520, Departement ISEN, 41 bd Vauban, 59046 Lille Cedex (France)

    2011-03-15

    Silicon nanowires (SiNWs) with different surface number density are fabricated using Chemical Vapor Deposition (CVD) method by controlling the catalyst droplet number density with in-situ evaporation. For comparison, another type of SiNWs is fabricated by Molecular Beam Epitaxy (MBE) method. To study these two types of SiNWs a general growth rate model is presented. The fit curves from this model are consistent with our experimental data. In both growing conditions the SiNW growth rate as a function of their diameter are compared and discussed. The p-type SiNWs have also been prepared by adding diborane into precursor. The doping metrology in an individual SiNW is realized by laser assisted Atom Probe Tomography (APT). We have shown that the doping atoms (e.g. B) can incorporate into SiNW and an accurate quantification can be given (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Atom probe tomography of Ni-base superalloys Allvac 718Plus and Alloy 718.

    Science.gov (United States)

    Viskari, L; Stiller, K

    2011-05-01

    Atom probe tomography (APT) allows near atomic scale compositional- and morphological studies of, e.g. matrix, precipitates and interfaces in a wide range of materials. In this work two Ni-base superalloys with similar compositions, Alloy 718 and its derivative Allvac 718Plus, are subject for investigation with special emphasis on the latter alloy. The structural and chemical nuances of these alloys are important for their properties. Of special interest are grain boundaries as their structure and chemistry are important for the materials' ability to resist rapid environmentally induced crack propagation. APT has proved to be suitable for analyses of these types of alloys using voltage pulsed APT. However, for investigations of specimens containing grain boundaries and other interfaces the risk for early specimen fracture is high. Analyses using laser pulsing impose lower electrical field on the specimen thereby significantly increasing the success rate of investigations. Here, the effect of laser pulsing was studied and the derived appropriate acquisition parameters were then applied for microstructural studies, from which initial results are shown. Furthermore, the influence of the higher evaporation field experienced by the hardening γ' Ni(3)(Al,Nb) precipitates on the obtained results is discussed.

  15. Characterization of RF He-N2/Ar mixture plasma via Langmuir probe and optical emission spectroscopy techniques

    Science.gov (United States)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Hussain, S. S.; Zakaullah, M.; Zaka-ul-Islam, M.

    2016-08-01

    A Magnetic Pole Enhanced inductively coupled RF H e - N 2 / A r plasma is characterized using a Langmuir probe and optical emission spectroscopy (OES) techniques. The effect of helium mixing on electron density ( n e ) and temperature ( T e ) , electron energy probability functions (EEPFs), [ N ] atomic density, and N 2 dissociation is investigated. A Langmuir probe and a zero slope method based on trace rare gas-optical emission spectroscopy (TRG-OES) are employed to measure the electron temperature. It is noted that the electron temperature shows an increasing trend for both methods. However, the temperature measured by a zero slope method T e ( Z . S ) approaches the temperature measured by a Langmuir probe; T e ( L . P ) at 56% and above helium concentration in the discharge. "Advance actinometry" is employed to monitor the variation in [ N ] atomic density with helium concentration and gas pressure. It is noted that [ N ] atomic density increases at 56% and above helium in the discharge, which is consistent with the trend of electron temperature and EEPFs. A drastic enhancement in N 2 dissociation fraction D 1 determined by "advance actinometry" is noted at 56% and above helium concentration in the mixture due to modifications in different population and depopulation mechanisms. However, it is also noted that the dissociation fraction D 2 determined by intensity ratio method increases linearly with helium addition.

  16. Probing molecular interaction between transferrin and anti-transferrin by atomic force microscope

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The interaction between transferrin (Tf) and its antibody was investigated by atomic force microscope. Tf-antibody was immobilized on the Au-coated glass slide, and the specific combination between antibody and antigen was also characterized by AFM. The results showed that holo-transferrin was jogged with anti-transferrin, and binded anti-tran- sferrin more tightly than apo-transferrin. The force- distance curves revealed that the affinity of anti-trans- ferrin and holo-transferrin was much stronger than that of apo-transferrin.

  17. Microstructural Characterization of Hierarchical Structured Surfaces by Atomic Force Microscopy

    Science.gov (United States)

    Ponomareva, A. A.; Moshnikov, V. A.; Suchaneck, G.

    2013-12-01

    In this work, we evaluate the hierarchical surface topography of reactively sputtered nanocrystalline Pb(Zr,Ti)O3 and TiO2 thin films as well as plasma-treated antireflective PET films by means of determining the fractal dimension and power spectral density (PSD) of surface topography recorded by atomic force microscopy (AFM). Local fractal dimension was obtained using the triangulation method. The PSDs of all samples were fitted to the k-correlation model (also called ABC model) valid for a self-affine surface topography. Fractal analysis of AFM images was shown to be an appropriate and easy to use tool for the characterization of hierarchical nanostructures.

  18. Atomic force microscope characterization of a resonating nanocantilever

    DEFF Research Database (Denmark)

    Abadal, G.; Davis, Zachary James; Borrise, X.;

    2003-01-01

    An atomic force microscope (AFM) is used as a nanometer-scale resolution tool for the characterization of the electromechanical behaviour of a resonant cantilever-based mass sensor. The cantilever is actuated electrostatically by applying DC and AC voltages from a driver electrode placed closely ...... and of the oscillation amplitude on the frequency of the AC voltage is measured by this technique and the results are fitted by a simple non-linear electromechanical model. (C) 2003 Elsevier Science B.V. All rights reserved....

  19. Near-grain-boundary characterization by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanick, A.K., E-mail: pramanick@nmlindia.org [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India); Sinha, A. [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India); Sastry, G.V.S. [Centre of Advanced Study, Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Ghosh, R.N. [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India)

    2009-05-15

    Characterization of near-grain boundary is carried out by atomic force microscopy (AFM). It has been observed to be the most suitable technique owing to its capability to investigate the surface at high resolution. Commercial purity-grade nickel processed under different conditions, viz., (i) cold-rolled and annealed and (ii) thermally etched condition without cold rolling, is considered in the present study. AFM crystallographic data match well with the standard data. Hence, it establishes two grain-boundary relations viz., plane matching and coincidence site lattice (CSL {Sigma}=9) relation for the two different sample conditions.

  20. Shaping the lens of the atom probe: Fabrication of site specific, oriented specimens and application to grain boundary analysis

    International Nuclear Information System (INIS)

    The random sampling provided by classical atom probe sample preparation methods is one of the major factors limiting the types of problems that can be addressed using this powerful technique. A focused ion beam enables not only site-specific preparation, but can also be used to give the specimen, which acts as the lens in an atom probe experiment, a specific shape. In this paper we present a technique that uses low accelerating voltages (10 and 5 kV) in the focused ion beam (FIB) to reproducibly produce specimens with selected grain boundaries <100 nm from the tip at any desired orientation. These tips have a high rate of successfully running in the atom probe and no Ga contamination within the region of interest. This technique is applied to the analysis of grain boundaries in a high purity iron wire and a strip-cast steel. Lattice resolution is achieved around the boundary in certain areas. Reconstruction of these datasets reveals the distribution of light and heavy elements around the boundary. Issues surrounding the uneven distribution of certain solute elements as a result of field-induced diffusion are discussed. -- Research highlights: → Damage free site specific samples can be made using FIB. → Crystallographic relationships across grain boundaries can be obtained from field desorption patterns. → Lattice resolution can be achieved at grain boundaries for matrix atoms. → Field evaporation artifacts are observed at grain boundaries for solute atoms.

  1. Probing biofouling resistant polymer brush surfaces by atomic force microscopy based force spectroscopy.

    Science.gov (United States)

    Schön, Peter; Kutnyanszky, Edit; ten Donkelaar, Bas; Santonicola, M Gabriella; Tecim, Tugba; Aldred, Nick; Clare, Anthony S; Vancso, G Julius

    2013-02-01

    The protein repellency and biofouling resistance of zwitterionic poly(sulfobetaine methacrylate)(pSBMA) brushes grafted via surface initiated polymerization (SIP) from silicon and glass substrata was assessed using atomic force microscopy (AFM) adherence experiments. Laboratory settlement assays were conducted with cypris larvae of the barnacle Balanus amphitrite. AFM adherence includes the determination of contact rupture forces when AFM probe tips are withdrawn from the substratum. When the surface of the AFM tip is modified, adherence can be assessed with chemical specifity using a method known as chemical force microscopy (CFM). In this study, AFM tips were chemically functionalized with (a) fibronectin- here used as model for a nonspecifically adhering protein - and (b) arginine-glycine-aspartic acid (RGD) peptide motifs covalently attached to poly(methacrylic acid) (PMAA) brushes as biomimics of cellular adhesion receptors. Fibronectin functionalized tips showed significantly reduced nonspecific adhesion to pSBMA-modified substrata compared to bare gold (2.3±0.75 nN) and octadecanethiol (ODT) self-assembled monolayers (1.3±0.75 nN). PMAA and PMAA-RGD modified probes showed no significant adhesion to pSBMA modified silicon substrata. The results gathered through AFM protein adherence studies were complemented by laboratory fouling studies, which showed no adhesion of cypris larvae of Balanus amphitrite on pSBMA. With regard to its unusually high non-specific adsorption to a wide variety of materials the behavior of fibronectin is analogous to the barnacle cyprid temporary adhesive that also binds well to surfaces differing in polarity, charge and free energy. The antifouling efficacy of pSBMA may, therefore, be directly related to the ability of this surface to resist nonspecific protein adsorption. PMID:23138001

  2. Analysis of strengthening in AA6111 during the early stages of aging: Atom probe tomography and yield stress modelling

    International Nuclear Information System (INIS)

    In this work, a series of aging treatments has been conducted on AA6111 alloy samples for various times at ambient temperature (so-called natural aging) and at temperatures between 60 and 180 °C (artificially aged). The time at artificial ageing was chosen such that samples with approximately the same yield stress were produced. The microstructures of these alloy samples have been carefully characterized using atom probe tomography together with advanced cluster-finding techniques in order to obtain quantitative information about the changes in distribution of both the solute clusters and early-stage precipitates that are formed. The size distribution of clusters has been mapped onto the glide plane and then the stress necessary for a dislocation to pass through the range of obstacles has been estimated using an areal glide model where the dislocation–obstacle interaction strength has been assumed to be related to the obstacle size on the glide plane. It is demonstrated that the contribution of cluster strengthening during artificial aging at higher temperatures is dominated by the high number density of small clusters (Guinier radius <1 nm), whereas the situation during room temperature natural aging is more complex

  3. Large Enhancement of Probe Amplification with Population Inversion in a Four-Level Atomic System with Vacuum-Induced Coherence

    Institute of Scientific and Technical Information of China (English)

    LI Jia-Hua; YANG Wen-Xing; LUO Jin-Ming; PENG Ju-Cun

    2005-01-01

    In this paper, we discuss and analyze theoretically probe absorption-amplification response in a four-level coherent atomic system with vacuum-induced coherence via changing the sign of the parameter f, with f denoting the ratio of a pair of dipole moments associated with a doublet of closely upper hyperfine sublevels. We find that the amplitude of the probe amplification for the case f = -1 can be about one order of magnitude larger than that achievable for the case f = 1. In addition, with respect to the case f = -1 the probe amplification can be maintained all the time with weak incoherent pumping for a wide range of the probe detuning.

  4. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    Science.gov (United States)

    Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.

    2016-06-01

    Three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36). ).

  5. Quenchant Characterization System Based on Application of Thermal Probes of Typical Steels

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-ting; ZHANG Li-wen; PEI Ji-bin; WANG Fu-gang; YU Cheng-xin

    2004-01-01

    A system was developed to identify characteristics of quenchants. It consists of computerized hardware,temperature acquisition software as well as changeable probes of steels. The feature of the ability to use probes made of any metallic material enables evaluation of hardening power of quenchants. Three thermal couples located on the same cross-section plane in the middle of probe's length give cooling curves that present cooling behavior at different depths from the surface of probe. Microstructure and hardness of the quenched probes on the same plane in the middle of probe's length from surface to center was investigated to estimate hardening effect. A number of quenchants were tested by this characterization system with several thermal probes of typical steels. Experimental data were stored in QuenDB quenchant database, which was designed for quenchants identification and hardness distribution storage.

  6. Multi-step process control and characterization of scanning probe lithography

    Science.gov (United States)

    Peterson, C. A.; Ruskell, T. G.; Pyle, J. L.; Workman, R. K.; Yao, X.; Hunt, J. P.; Sarid, D.; Parks, H. G.; Vermeire, B.

    An atomic force microscope with a conducting tip (CT-AFM) was used to fabricate and characterize nanometer scale lines of (1) silicon oxide and (2) silicon nitride on H-terminated n-type silicon (100) wafers. In process (1), a negative bias was applied to the tip of the CT-AFM system and the resulting electric field caused electrolysis of ambient water vapor and local oxidation of the silicon surface. In addition, the accompanying current was detected by a sub-pA current amplifier. In process (2), the presence of a nitrogen atmosphere containing a small partial pressure of ammonia resulted in the local nitridation of the surface. The CT-AFM system was also used to locate and study the dielectric properties of the silicon-oxide lines as well as copper islands buried under 20 nm of silicon dioxide. A computer-controlled feedback system and raster scanning of the sample produced simultaneous topographic and Fowler-Nordheim tunneling maps of the structures under study. Detailed aspects of nanolithography and local-probe Fowler-Nordheim characterization using a CT-AFM will be discussed.

  7. Thermal stability of TiAlN/CrN multilayer coatings studied by atom probe tomography.

    Science.gov (United States)

    Choi, Pyuck-Pa; Povstugar, Ivan; Ahn, Jae-Pyeong; Kostka, Aleksander; Raabe, Dierk

    2011-05-01

    This study is about the microstructural evolution of TiAlN/CrN multilayers (with a Ti:Al ratio of 0.75:0.25 and average bilayer period of 9 nm) upon thermal treatment. Pulsed laser atom probe analyses were performed in conjunction with transmission electron microscopy and X-ray diffraction. The layers are found to be thermally stable up to 600 °C. At 700 °C TiAlN layers begin to decompose into Ti- and Al-rich nitride layers in the out-of-plane direction. Further increase in temperature to 1000 °C leads to a strong decomposition of the multilayer structure as well as grain coarsening. Layer dissolution and grain coarsening appear to begin at the surface. Domains of AlN and TiCrN larger than 100 nm are found, together with smaller nano-sized AlN precipitates within the TiCrN matrix. Fe and V impurities are detected in the multilayers as well, which diffuse from the steel substrate into the coating along columnar grain boundaries. PMID:21146308

  8. Uranium Isotopic Ratio Measurements of U3O8 Reference Materials by Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fahey, Albert J.; Perea, Daniel E.; Bartrand, Jonah AG; Arey, Bruce W.; Thevuthasan, Suntharampillai

    2016-01-01

    We report results of measurements of isotopic ratios obtained with atom probe tomography on U3O8 reference materials certified for their isotopic abundances of uranium. The results show good agreement with the certified values. High backgrounds due to tails from adjacent peaks complicate the measurement of the integrated peak areas as well as the fact that only oxides of uranium appear in the spectrum, the most intense of which is doubly charged. In addition, lack of knowledge of other instrumental parameters, such as the dead time, may bias the results. Isotopic ratio measurements can be performed at the nanometer-scale with the expectation of sensible results. The abundance sensitivity and mass resolving power of the mass spectrometer are not sufficient to compete with magnetic-sector instruments but are not far from measurements made by ToF-SIMS of other isotopic systems. The agreement of the major isotope ratios is more than sufficient to distinguish most anthropogenic compositions from natural.

  9. Atom probe study of vanadium interphase precipitates and randomly distributed vanadium precipitates in ferrite.

    Science.gov (United States)

    Nöhrer, M; Zamberger, S; Primig, S; Leitner, H

    2013-01-01

    Atom probe tomography and transmission electron microscopy were used to examine the precipitation reaction in the austenite and ferrite phases in vanadium micro-alloyed steel after a thermo-mechanical process. It was observed that only in the ferrite phase precipitates could be found, whereupon two different types were detected. Thus, the aim was to reveal the difference between these two types. The first type was randomly distributed precipitates from V supersaturated ferrite and the second type V interphase precipitates. Not only the arrangement of the particles was different also the chemical composition. The randomly distributed precipitates consisted of V, C and N in contrast to that the interphase precipitates showed a composition of V, C and Mn. Furthermore the randomly distributed precipitates had maximum size of 20 nm and the interphase precipitates a maximum size of 15 nm. It was assumed that the reason for these differences is caused by the site in which they were formed. The randomly distributed precipitates were formed in a matrix consisting mainly of 0.05 at% C, 0.68 at% Si, 0.03 at% N, 0.145 at% V and 1.51 at% Mn. The interphase precipitates were formed in a region with a much higher C, Mn and V content. PMID:24041583

  10. Atom probe tomography analysis of high dose MA957 at selected irradiation temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Nathan A. [University of California at Berkeley, 3117 Etcheverry Hall, Berkeley, CA 94720 (United States); Stergar, Erich [University of California at Berkeley, 3117 Etcheverry Hall, Berkeley, CA 94720 (United States); SCK-CEN, BE-2400, Mol (Belgium); Toloczko, Mychailo [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Hosemann, Peter [University of California at Berkeley, 3117 Etcheverry Hall, Berkeley, CA 94720 (United States)

    2015-04-15

    Oxide dispersion strengthened (ODS) alloys are meritable structural materials for nuclear reactor systems due to the exemplary resistance to radiation damage and high temperature creep. Summarized in this work are atom probe tomography (APT) investigations on a heat of MA957 that underwent irradiation in the form of in-reactor creep specimens in the Fast Flux Test Facility–Materials Open Test Assembly (FFTF–MOTA) for the Liquid Metal Fast Breeder Reactor (LMFBR) program. The oxide precipitates appear stable under irradiation at elevated temperature over extended periods of time. Nominally, the precipitate chemistry is unchanged by the accumulated dose; although, evidence suggests that ballistic dissolution and reformation processes are occurring at all irradiation temperatures. At 412 °C–109 dpa, chromium enrichments – consistent with the α′ phase – appear between the oxide precipitates, indicating radiation induced segregation. Grain boundaries, enriched with several elements including nickel and titanium, are observed at all irradiation conditions. At 412 °C–109 dpa, the grain boundaries are also enriched in molecular titanium oxide (TiO)

  11. Atom probe tomography investigation of lath boundary segregation and precipitation in a maraging stainless steel.

    Science.gov (United States)

    Thuvander, Mattias; Andersson, Marcus; Stiller, Krystyna

    2013-09-01

    Lath boundaries in a maraging stainless steel of composition 13Cr-8Ni-2Mo-2Cu-1Ti-0.7Al-0.3Mn-0.2Si-0.03C (at%) have been investigated using atom probe tomography following aging at 475 °C for up to 100 h. Segregation of Mo, Si and P to the lath boundaries was observed already after 5 min of aging, and the amount of segregation increases with aging time. At lath boundaries also precipitation of η-Ni₃(Ti, Al) and Cu-rich 9R, in contact with each other, takes place. These co-precipitates grow with time and because of coarsening the area number density decreases. After 100 h of aging a ∼5 nm thick film-like precipitation of a Mo-rich phase was observed at the lath boundaries. From the composition of the film it is suggested that the phase in question is the quasicrystalline R' phase. The film is perforated with Cu-rich 9R and η-Ni₃(Ti, Al) co-precipitates. Not all precipitate types present in the matrix do precipitate at the lath boundaries; the Si-containing G phase and γ'-Ni₃(Ti, Al, Si) and the Cr-rich α' phase were not observed at the lath boundaries.

  12. A versatile LabVIEW and FPGA-based scanned probe microscope for in-operando electronic device characterization

    CERN Document Server

    Berger, Andrew J; Jacob, Jan; Young, Justin R; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P; Johnston-Halperin, Ezekiel; Pelekhov, Denis V; Hammel, P Chris

    2014-01-01

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In-operando characterization of such devices by scanned probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanned probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically-biased graphene FET device. The c...

  13. Quantitative chemical-structure evaluation using atom probe tomography: Short-range order analysis of Fe–Al

    Energy Technology Data Exchange (ETDEWEB)

    Marceau, R.K.W., E-mail: r.marceau@deakin.edu.au [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia); Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf (Germany); Ceguerra, A.V.; Breen, A.J. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Raabe, D. [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf (Germany); Ringer, S.P. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia)

    2015-10-15

    Short-range-order (SRO) has been quantitatively evaluated in an Fe–18Al (at%) alloy using atom probe tomography (APT) data and by calculation of the generalised multicomponent short-range order (GM-SRO) parameters, which have been determined by shell-based analysis of the three-dimensional atomic positions. The accuracy of this method with respect to limited detector efficiency and spatial resolution is tested against simulated D0{sub 3} ordered data. Whilst there is minimal adverse effect from limited atom probe instrument detector efficiency, the combination of this with imperfect spatial resolution has the effect of making the data appear more randomised. The value of lattice rectification of the experimental APT data prior to GM-SRO analysis is demonstrated through improved information sensitivity. - Highlights: • Short-range-order (SRO) is quantitatively evaluated using atom probe tomography data. • Chemical species-specific SRO parameters have been calculated. • The accuracy of this method is tested against simulated D0{sub 3} ordered data. • Imperfect spatial resolution combined with finite detector efficiency causes a randomising effect. • Lattice rectification of the data prior to GM-SRO analysis is demonstrated to improve information sensitivity.

  14. Atmospheric Solid Analysis Probe-Ion Mobility Mass Spectrometry: An Original Approach to Characterize Grafting on Cyclic Olefin Copolymer Surfaces.

    Science.gov (United States)

    Vieillard, Julien; Hubert-Roux, Marie; Brisset, Florian; Soulignac, Cecile; Fioresi, Flavia; Mofaddel, Nadine; Morin-Grognet, Sandrine; Afonso, Carlos; Le Derf, Franck

    2015-12-01

    A cyclic olefin copolymer (COC) was grafted with aryl layers from aryldiazonium salts, and then we combined infrared spectrometry, atomic force microscopy (AFM), and ion mobility mass spectrometry with atmospheric solid analysis probe ionization (ASAP-IM-MS) to characterize the aryl layers. ASAP is a recent atmospheric ionization method dedicated to the direct analysis of solid samples. We demonstrated that ASAP-IM-MS is complementary to other techniques for characterizing bromine and sulfur derivatives of COC on surfaces. ASAP-IM-MS was useful for optimizing experimental grafting conditions and to elucidate hypotheses around aryl layer formation during the grafting process. Thus, ASAP-IM-MS is a good candidate tool to characterize covalent grafting on COC surfaces.

  15. Development of Two-Photon Pump Polarization Spectroscopy Probe Technique Tpp-Psp for Measurements of Atomic Hydrogen .

    Science.gov (United States)

    Satija, Aman; Lucht, Robert P.

    2015-06-01

    Atomic hydrogen (H) is a key radical in combustion and plasmas. Accurate knowledge of its concentration can be used to better understand transient phenomenon such as ignition and extinction in combustion environments. Laser induced polarization spectroscopy is a spatially resolved absorption technique which we have adapted for quantitative measurements of H atom. This adaptation is called two-photon pump, polarization spectroscopy probe technique (TPP-PSP) and it has been implemented using two different laser excitation schemes. The first scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-3P levels using a circularly polarized 656-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 656 nm. As a result, the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. The laser beams were created by optical parametric generation followed by multiple pulse dye amplification stages. This resulted in narrow linewidth beams which could be scanned in frequency domain and varied in energy. This allowed us to systematically investigate saturation and Stark effect in 2S-3P transitions with the goal of developing a quantitative H atom measurement technique. The second scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-4P transitions using a circularly polarized 486-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 486 nm. As a result the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. A dye laser was pumped by third harmonic of a Nd:YAG laser to create a laser beam

  16. Interpretation of atom probe tomography data for the intermetallic TiAl+Nb by means of field evaporation simulation

    KAUST Repository

    Boll, Torben

    2013-01-01

    In this paper simulations of the field evaporation process during field ion microscopy (FIM) and atom probe tomography (APT) are presented and compared with experimental data. The Müller-Schottky-model [1] was extended to include the local atomic arrangement on the evaporation process of atoms. This arrangement was described by the sum of the next-neighbor-binding-energies, which differ for an atom of type A, depending on how many A-A, B-B or A-B bonds are present. Thus simulations of APT-data of intermetallic phases become feasible. In this study simulations of L10-TiAl with additions of Nb are compared with experimental data. Certain artifacts, which appear for experimental data are treated as well. © 2012 Elsevier B.V.

  17. An automated Langmuir probe controller for plasma characterization

    Science.gov (United States)

    Bustos, A.; Juarez, A. M.; de Urquijo, J.; Muñoz, M.

    2016-08-01

    We present the design, construction and test of an automated electronic controller for a Langmuir plasma probe. The novel aspect of this system lies in the isolation of the high voltage present in the discharge from the grounded reference of the controller. This controller detects currents over the range from  ±1 μA to  ±50 mA, using dynamic and automated switching of a transresistance amplifier. This automated Langmuir probe (LP) system has been successfully tested in a glow discharge in argon at 0.8 and 10 Torr.

  18. Ultrashort pulse characterization by frequency-resolved pump-probe

    NARCIS (Netherlands)

    Pshenichnikov, MS; Baltuska, A; de Haan, F; Wiersma, DA; Elsaesser, T; Mukamel, S; Murnane, MM; Scherer, NF

    2001-01-01

    We present a novel method for measuring amplitude and phase of ultrashort optical pulses. The technique makes use of frequency-resolved pump-probe geometry that is widely used in femtochemistry and femtobiology. The experimental realization of the method is demonstrated.

  19. Design - manufacturing and characterization of specific ultrasonic probes

    International Nuclear Information System (INIS)

    Optimization of ultrasonic examinations requires essentially to determine precisely parameters used for manufacturing of probes and to check characteristics of beams used. The system presented permits an automatic determination of dimensions of beams in conditions which are totally representative of those of their use

  20. Characterization of new drug delivery nanosystems using atomic force microscopy

    Science.gov (United States)

    Spyratou, Ellas; Mourelatou, Elena A.; Demetzos, C.; Makropoulou, Mersini; Serafetinides, A. A.

    2015-01-01

    Liposomes are the most attractive lipid vesicles for targeted drug delivery in nanomedicine, behaving also as cell models in biophotonics research. The characterization of the micro-mechanical properties of drug carriers is an important issue and many analytical techniques are employed, as, for example, optical tweezers and atomic force microscopy. In this work, polyol hyperbranched polymers (HBPs) have been employed along with liposomes for the preparation of new chimeric advanced drug delivery nanosystems (Chi-aDDnSs). Aliphatic polyester HBPs with three different pseudogenerations G2, G3 and G4 with 16, 32, and 64 peripheral hydroxyl groups, respectively, have been incorporated in liposomal formulation. The atomic force microscopy (AFM) technique was used for the comparative study of the morphology and the mechanical properties of Chi-aDDnSs and conventional DDnS. The effects of both the HBPs architecture and the polyesters pseudogeneration number in the stability and the stiffness of chi-aDDnSs were examined. From the force-distance curves of AFM spectroscopy, the Young's modulus was calculated.

  1. Probing Atomic Structure and Majorana Wavefunctions in Mono-Atomic Fe-chains on Superconducting Pb-Surface

    CERN Document Server

    Pawlak, Remy; Klinovaja, Jelena; Meier, Tobias; Kawai, Shigeki; Glatzel, Thilo; Loss, Daniel; Meyer, Ernst

    2015-01-01

    Motivated by the striking promise of quantum computation, Majorana bound states (MBSs) in solid-state systems have attracted wide attention in recent years. In particular, the wavefunction localization of MBSs is a key feature and crucial for their future implementation as qubits. Here, we investigate the spatial and electronic characteristics of topological superconducting chains of iron atoms on the surface of Pb(110) by combining scanning tunneling microscopy (STM) and atomic force microscopy (AFM). We demonstrate that the Fe chains are mono-atomic, structured in a linear fashion, and exhibit zero-bias conductance peaks at their ends which we interprete as signature for a Majorana bound state. Spatially resolved conductance maps of the atomic chains reveal that the MBSs are well localized at the chain ends (below 25 nm), with two localization lengths as predicted by theory. Our observation lends strong support to use MBSs in Fe chains as qubits for quantum computing devices.

  2. Using Atom-Probe Tomography to Understand Zn O ∶Al /SiO 2/Si Schottky Diodes

    Science.gov (United States)

    Jaramillo, R.; Youssef, Amanda; Akey, Austin; Schoofs, Frank; Ramanathan, Shriram; Buonassisi, Tonio

    2016-09-01

    We use electronic transport and atom-probe tomography to study Zn O ∶Al /SiO 2/Si Schottky diodes on lightly doped n - and p -type Si. We vary the carrier concentration in the ZnO ∶Al films by 2 orders of magnitude, but the Schottky barrier height remains nearly constant. Atom-probe tomography shows that Al segregates to the interface, so that the ZnO ∶Al at the junction is likely to be metallic even when the bulk of the ZnO ∶Al film is semiconducting. We hypothesize that the observed Fermi-level pinning is connected to the insulator-metal transition in doped ZnO. This implies that tuning the band alignment at oxide/Si interfaces may be achieved by controlling the transition between localized and extended states in the oxide, thereby changing the orbital hybridization across the interface.

  3. Atom probe tomography investigation of lath boundary segregation and precipitation in a maraging stainless steel

    International Nuclear Information System (INIS)

    Lath boundaries in a maraging stainless steel of composition 13Cr–8Ni–2Mo–2Cu–1Ti–0.7Al–0.3Mn–0.2Si–0.03C (at%) have been investigated using atom probe tomography following aging at 475 °C for up to 100 h. Segregation of Mo, Si and P to the lath boundaries was observed already after 5 min of aging, and the amount of segregation increases with aging time. At lath boundaries also precipitation of η-Ni3(Ti, Al) and Cu-rich 9R, in contact with each other, takes place. These co-precipitates grow with time and because of coarsening the area number density decreases. After 100 h of aging a ∼5 nm thick film-like precipitation of a Mo-rich phase was observed at the lath boundaries. From the composition of the film it is suggested that the phase in question is the quasicrystalline R′ phase. The film is perforated with Cu-rich 9R and η-Ni3(Ti, Al) co-precipitates. Not all precipitate types present in the matrix do precipitate at the lath boundaries; the Si-containing G phase and γ′-Ni3(Ti, Al, Si) and the Cr-rich α′ phase were not observed at the lath boundaries. - Highlights: ► Lath boundaries in a maraging steel were analyzed by APT. ► Segregation of Mo, Si and P was measured. ► Precipitation of η-Ni3(Ti, Al) and Cu-rich 9R was observed. ► After 100 h of aging a quasicrystalline Mo-rich film was observed

  4. Atom probe tomography investigation of lath boundary segregation and precipitation in a maraging stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Thuvander, Mattias, E-mail: mattias.thuvander@chalmers.se [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Andersson, Marcus [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); R and D Centre, Sandvik Materials Technology, SE-811 81 Sandviken (Sweden); Stiller, Krystyna [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2013-09-15

    Lath boundaries in a maraging stainless steel of composition 13Cr–8Ni–2Mo–2Cu–1Ti–0.7Al–0.3Mn–0.2Si–0.03C (at%) have been investigated using atom probe tomography following aging at 475 °C for up to 100 h. Segregation of Mo, Si and P to the lath boundaries was observed already after 5 min of aging, and the amount of segregation increases with aging time. At lath boundaries also precipitation of η-Ni{sub 3}(Ti, Al) and Cu-rich 9R, in contact with each other, takes place. These co-precipitates grow with time and because of coarsening the area number density decreases. After 100 h of aging a ∼5 nm thick film-like precipitation of a Mo-rich phase was observed at the lath boundaries. From the composition of the film it is suggested that the phase in question is the quasicrystalline R′ phase. The film is perforated with Cu-rich 9R and η-Ni{sub 3}(Ti, Al) co-precipitates. Not all precipitate types present in the matrix do precipitate at the lath boundaries; the Si-containing G phase and γ′-Ni{sub 3}(Ti, Al, Si) and the Cr-rich α′ phase were not observed at the lath boundaries. - Highlights: ► Lath boundaries in a maraging steel were analyzed by APT. ► Segregation of Mo, Si and P was measured. ► Precipitation of η-Ni{sub 3}(Ti, Al) and Cu-rich 9R was observed. ► After 100 h of aging a quasicrystalline Mo-rich film was observed.

  5. Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity

    DEFF Research Database (Denmark)

    Gammelmark, S.; Molmer, K.; Alt, W.;

    2014-01-01

    We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian...... manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory...

  6. Controllable growth and characterizations of hybrid spiral-like atomically thin molybdenum disulfide

    Science.gov (United States)

    Hao, Song; Yang, Bingchu; Gao, Yongli

    2016-10-01

    Monolayer MoS2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in novel electronic and optoelectronic devices. Here, we reported controlled vapor phase growth of hybrid spiral-like MoS2 crystals investigated by multiple means of X-Ray photoemission spectroscopy, scanning electron microscopy, atomic force microscopy, kelvin probe force microscopy, Raman and Photoluminescence techniques. Morphological characterizations reveal an intriguing hybrid spiral-like MoS2 feature whose lower planes are AB Bernal stacking and upper structure is spiral. We ascribe the hybrid spiral-like structure to a screw dislocation drive growth mechanism owing to lower supersaturation and layer-by-layer growth mode. In addition, the electrostatic properties of MoS2 microflakes with hybrid spiral structures are obvious inhomogeneous and dependent on morphology manifested by kelvin probe force microscopy. Our work deepens the understanding of growth mechanisms of CVD-grown MoS2, which is also adoptable to other TMDC materials.

  7. Elastic and viscoelastic characterization of inhomogeneous polymers by bimodal atomic force microscopy

    Science.gov (United States)

    Nguyen, Hung K.; Ito, Makiko; Nakajima, Ken

    2016-08-01

    The elastic and viscoelastic responses of inhomogeneous polymers upon interacting with an atomic force microscopy (AFM) probe are simultaneously characterized by a bimodal AFM approach namely the amplitude- and frequency-modulation (AM–FM) method. In this approach, the AFM probe is operated in the AM mode at the first flexural frequency and in the FM mode at a higher flexural frequency. The AM mode provides information about the viscoelasticity of polymers in terms of the mechanical loss tangent, whereas the modulus of polymers is obtained as a function of the frequency shift of flexural frequencies in both modes. For a glassy polymer blend, the AM–FM method provides a consistent result in both the elastic modulus and loss tangent in comparison with those obtained by other methods. Moreover, a significant improvement of the contrast and lateral resolution in the AM–FM modulus image can be observed. However, the current approach shows a substantial increase in the modulus of rubbery polymers.

  8. Identification of Radiation-Induced Segregation in Ion-irradiated Stainless Steel 316 using Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gyeong-Geun; Jin, Hyung-Ha; Chang, Kunok; Kwon, Junhyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Various kinds of defects are produced by the irradiation of energetic particles onto a structural material. The defect fluxes such as mobile vacancies and self-interstitial atoms cause the diffusion of the solute atoms in the matrix. The preferential interaction of the solute with defects induces the enrichment or depletion of the solutes at the defect sinks such as the grain boundaries, and surfaces. These phenomena are generally known as radiation-induced segregation (RIS). Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) are generally used as basic analysis techniques to obtain a concentration profile of RIS arising from irradiation. However, the resolution of EDS is limited due to beam broadening, and the overlapping of the probed volume with the matrix prohibits a quantitative analysis of the concentration changes. In the current work, we introduced atom probe tomography (APT) to analyze RIS in SS 316. Various types of radiation-induced defects were identified and the compositional characteristics were quantitatively provided from a wide view point. The measured concentrations were compared with values in the literature. This work can provide a fundamental understanding of the RIS behavior in ion-irradiated SS 316. In this study, an APT analysis of RIS in ion-irradiated SS316 was performed. Various types of irradiation defects were observed. Si atoms are located at the core structures of dislocation loops and clusters.

  9. Electrochemical techniques for characterization of stem-loop probe and linear probe-based DNA sensors.

    Science.gov (United States)

    Lai, Rebecca Y; Walker, Bryce; Stormberg, Kent; Zaitouna, Anita J; Yang, Weiwei

    2013-12-15

    Here we present a summary of the sensor performance of the stem-loop probe (SLP) and linear probe (LP) electrochemical DNA sensors when interrogated using alternating current voltammetry (ACV), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Specifically, we identified one critical parameter for each voltammetric technique that can be adjusted for optimal sensor performance. Overall, the SLP sensor displayed good sensor performance (i.e., 60+% signal attenuation in the presence of the target) over a wider range of experimental conditions when compared to the LP sensor. When used with ACV, the optimal frequency range was found to be between 5 and 5000 Hz, larger than the 5-100 Hz range observed with the LP sensor. A similar trend was observed for the two sensors in CV; the LP sensor was operational only at scan rates between 30 and 100 V/s, whereas the SLP sensor performed well at scan rates between 1 and 1000 V/s. Unlike ACV and CV, DPV has demonstrated to be a more versatile sensor interrogation technique for this class of sensors. Despite the minor differences in total signal attenuation upon hybridization to the target DNA, both SLP and LP sensors performed optimally under most pulse widths used in this study. More importantly, when used with longer pulse widths, both sensors showed "signal-on" behavior, which is generally more desirable for sensor applications.

  10. Coke Formation in a Zeolite Crystal During the Methanol-to-Hydrocarbons Reaction as Studied with Atom Probe Tomography.

    Science.gov (United States)

    Schmidt, Joel E; Poplawsky, Jonathan D; Mazumder, Baishakhi; Attila, Özgün; Fu, Donglong; de Winter, D A Matthijs; Meirer, Florian; Bare, Simon R; Weckhuysen, Bert M

    2016-09-01

    Understanding the formation of carbon deposits in zeolites is vital to developing new, superior materials for various applications, including oil and gas conversion processes. Herein, atom probe tomography (APT) has been used to spatially resolve the 3D compositional changes at the sub-nm length scale in a single zeolite ZSM-5 crystal, which has been partially deactivated by the methanol-to-hydrocarbons reaction using (13) C-labeled methanol. The results reveal the formation of coke in agglomerates that span length scales from tens of nanometers to atomic clusters with a median size of 30-60 (13) C atoms. These clusters correlate with local increases in Brønsted acid site density, demonstrating that the formation of the first deactivating coke precursor molecules occurs in nanoscopic regions enriched in aluminum. This nanoscale correlation underscores the importance of carefully engineering materials to suppress detrimental coke formation.

  11. Coke Formation in a Zeolite Crystal During the Methanol-to-Hydrocarbons Reaction as Studied with Atom Probe Tomography.

    Science.gov (United States)

    Schmidt, Joel E; Poplawsky, Jonathan D; Mazumder, Baishakhi; Attila, Özgün; Fu, Donglong; de Winter, D A Matthijs; Meirer, Florian; Bare, Simon R; Weckhuysen, Bert M

    2016-09-01

    Understanding the formation of carbon deposits in zeolites is vital to developing new, superior materials for various applications, including oil and gas conversion processes. Herein, atom probe tomography (APT) has been used to spatially resolve the 3D compositional changes at the sub-nm length scale in a single zeolite ZSM-5 crystal, which has been partially deactivated by the methanol-to-hydrocarbons reaction using (13) C-labeled methanol. The results reveal the formation of coke in agglomerates that span length scales from tens of nanometers to atomic clusters with a median size of 30-60 (13) C atoms. These clusters correlate with local increases in Brønsted acid site density, demonstrating that the formation of the first deactivating coke precursor molecules occurs in nanoscopic regions enriched in aluminum. This nanoscale correlation underscores the importance of carefully engineering materials to suppress detrimental coke formation. PMID:27485276

  12. A single-atom detector integrated on an atom chip: fabrication, characterization and application

    Science.gov (United States)

    Heine, D.; Rohringer, W.; Fischer, D.; Wilzbach, M.; Raub, T.; Loziczky, S.; Liu, XiYuan; Groth, S.; Hessmo, B.; Schmiedmayer, J.

    2010-09-01

    We describe a robust and reliable fluorescence detector for single atoms that is fully integrated on an atom chip. The detector allows spectrally and spatially selective detection of atoms, reaching a single-atom detection efficiency of 66%. It consists of a tapered lensed single-mode fiber for precise delivery of excitation light and a multi-mode fiber to collect the fluorescence. The fibers are mounted in lithographically defined holding structures on the atom chip. Neutral 87Rb atoms propagating freely in a magnetic guide are detected and the noise of their fluorescence emission is analyzed. The variance of the photon distribution allows us to determine the number of detected photons per atom and from there the atom detection efficiency. The second-order intensity correlation function of the fluorescence shows near-perfect photon anti-bunching and signs of damped Rabi oscillations. With simple improvements, one can increase the detection efficiency to 95%.

  13. Ultrafast probing of the x-ray-induced lattice and electron dynamics in graphite at atomic-resolution

    Energy Technology Data Exchange (ETDEWEB)

    Hau-Riege, S

    2010-10-07

    We used LCLS pulses to excite thin-film and bulk graphite with various different microstructures, and probed the ultrafast ion and electron dynamics through Bragg and x-ray Thomson scattering (XRTS). We pioneered XRTS at LCLS, making this technique viable for other users. We demonstrated for the first time that the LCLS can be used to characterize warm-dense-matter through Bragg and x-ray Thomson scattering. The warm-dense-matter conditions were created using the LCLS beam. Representative examples of the results are shown in the Figure above. In our experiment, we utilized simultaneously both Bragg and two Thomson spectrometers. The Bragg measurements as a function of x-ray fluence and pulse length allows us to characterize the onset of atomic motion at 2 keV with the highest resolution to date. The Bragg detector was positioned in back-reflection, providing us access to scattering data with large scattering vectors (nearly 4{pi}/{lambda}). We found a clear difference between the atomic dynamics for 70 and 300 fs pulses, and we are currently in the process of comparing these results to our models. The outcome of this comparison will have important consequences for ultrafast diffractive imaging, for which it is still not clear if atomic resolution can truly be achieved. The backward x-ray Thomson scattering data suggests that the average graphite temperature and ionization was 10 eV and 1.0, respectively, which agrees with our models. In the forward scattering data, we observed an inelastic feature in the Thomson spectrum that our models currently do not reproduce, so there is food for thought. We are in the process of writing these results up. Depending on if we can combine the Bragg and Thomson data or not, we plan to publish them in a single paper (e.g. Nature or Science) or as two separate papers (e.g. two Phys. Rev. Lett.). We will present the first analysis of the results at the APS Plasma Meeting in November 2010. We had a fantastic experience performing our

  14. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy.

    Science.gov (United States)

    Lee, Jung Ah; Lim, Young Rok; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-21

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes. PMID:27640642

  15. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

    Science.gov (United States)

    Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-01

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  16. The effect orientation of features in reconstructed atom probe data on the resolution and measured composition of T1 plates in an A2198 aluminium alloy.

    Science.gov (United States)

    Mullin, Maria A; Araullo-Peters, Vicente J; Gault, Baptiste; Cairney, Julie M

    2015-12-01

    Artefacts in atom probe tomography can impact the compositional analysis of microstructure in atom probe studies. To determine the integrity of information obtained, it is essential to understand how the positioning of features influences compositional analysis. By investigating the influence of feature orientation within atom probe data on measured composition in microstructural features within an AA2198 Al alloy, this study shows differences in the composition of T1 (Al2CuLi) plates that indicates imperfections in atom probe reconstructions. The data fits a model of an exponentially-modified Gaussian that scales with the difference in evaporation field between solutes and matrix. This information provides a guide for obtaining the most accurate information possible.

  17. Clustering Effects Under Irradiation in Fe-0.1%Cu Alloy : An Atomic Scale Investigation with the Tomographic Atom Probe

    OpenAIRE

    Pareige, P.; Welzel, S; Auger, P.

    1996-01-01

    In order to understand the effect of displacement cascades on the evolution of the microstructure of ferritic low copper supersaturated materials, analyses by 3D atomic tomography of neutron, electron and self ion irradiated Fe-0.1%Cu, were performed. This alloy was chosen because of its low copper concentration, close to that of french pressure vessel steels. The comparison of the microstructure evolutions in these irradiated specimens reveals the appearance of tiny copper "clusters" or "agg...

  18. Characterization of torque-spectroscopy techniques for probing rotary nanomotors

    NARCIS (Netherlands)

    Van Oene, M.M.

    2016-01-01

    This thesis describes developments in the characterization of torque-spectroscopy techniques, in particular magnetic and optical tweezers, with the goal of employing these techniques in studies on the bacterial flagellar motor of Escherichia coli.

  19. Microstructured Reactors Designed by Stereolithography and Characterized by Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    S. Corbel

    2008-01-01

    Full Text Available The main objective of this research was to define a structured and functionalized support for future biomedical applications (model of “low-density bioarray”. The experiments were carried out by using stereolithography process with a special SU-8 photoresist and the reproducibility of the method was studied by analyzing the surface profile of the support. Finally, a matrix of regular controlled sized wells was fabricated. Chemical reactions leading to covalent grafting were run to demonstrate that the inner surface of the wells remains still reactive after polymerization. The grafting of fluorophores with carboxylic functions activated by N-hydroxysuccinimide was studied as function of time, in order to determine the best reactions, conditions. Then, the grafting of two distinct fluorescent probes was led simultaneously inside the wells, showing the possibility of spatial localization of diverse reactions on the same support. The covalent and localized bindings were confirmed by fluorescence spectroscopy and microscopy analyses.

  20. Probing the mechanical properties of TNF-α stimulated endothelial cell with atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Sei-Young Lee

    2011-01-01

    Full Text Available Sei-Young Lee1,2, Ana-Maria Zaske3, Tommaso Novellino1,4*, Delia Danila3, Mauro Ferrari1,5*, Jodie Conyers3, Paolo Decuzzi1,6*1Department of Nanomedicine and Biomedical Engineering, The University of Texas Medical School at Houston, Houston, TX, USA; 2Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA; 3CeTIR – Center for Translational Injury Research, The University of Texas Health Science Center at Houston, Houston, TX, USA; 4Department of Biomedical Engineering, Biomedical Campus University of Rome, Italy; 5MD Anderson Cancer Center, Houston, TX, USA; 6BioNEM – Center of Bio-Nanotechnology and Engineering for Medicine, University of Magna Graecia, Catanzaro, Italy; *Currently at Department of Nanomedicine and Biomedical Engineering, The Methodist Hospital Research Institute, Houston, TX, USAAbstract: TNF-α (tumor necrosis factor-α is a potent pro-inflammatory cytokine that regulates the permeability of blood and lymphatic vessels. The plasma concentration of TNF-α is elevated (> 1 pg/mL in several pathologies, including rheumatoid arthritis, atherosclerosis, cancer, pre-eclampsia; in obese individuals; and in trauma patients. To test whether circulating TNF-α could induce similar alterations in different districts along the vascular system, three endothelial cell lines, namely HUVEC, HPMEC, and HCAEC, were characterized in terms of 1 mechanical properties, employing atomic force microscopy; 2 cytoskeletal organization, through fluorescence microscopy; and 3 membrane overexpression of adhesion molecules, employing ELISA and immunostaining. Upon stimulation with TNF-α (10 ng/mL for 20 h, for all three endothelial cells, the mechanical stiffness increased by about 50% with a mean apparent elastic modulus of E ~5 ± 0.5 kPa (~3.3 ± 0.35 kPa for the control cells; the density of F-actin filaments increased in the apical and median planes; and the ICAM-1 receptors were overexpressed compared with

  1. Characterization and Detection of Biological Weapons with Atomic Force Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Malkin, A J; Plomp, M; Leighton, T J; McPherson, A

    2006-09-25

    Critical gaps exist in our capabilities to rapidly characterize threat agents which could be used in attacks on facilities and military forces. DNA-based PCR and immunoassay-based techniques provide unique identification of species, strains and protein signatures of pathogens. However, differentiation between naturally occurring and weaponized bioagents and the identification of formulation signatures are beyond current technologies. One of the most effective and often the only definitive means to identify a threat agent is by its direct visualization. Atomic force microscopy (AFM) is a rapid imaging technique that covers the size range of most biothreat agents (several nanometers to tens of microns), is capable of resolving pathogen morphology and structure, and could be developed into a portable device for biological weapons (BW) field characterization. AFM can detect pathogens in aerosol, liquid, surface and soil samples while concomitantly acquiring their weaponization and threat agent digital signatures. BW morphological and structural signatures, including modifications to pathogen microstructural architecture and topology that occur during formulation and weaponization, provide the means for their differentiation from crude or purified unformulated agent, processing signatures, as well as assessment of their potential for dispersion, inhalation and environmental persistence. AFM visualization of pathogen morphology and architecture often provides valuable digital signatures and allows direct detection and identification of threat agents. We have demonstrated that pathogens, spanning the size range from several nanometers for small agricultural satellite viruses to almost half micron for pox viruses, and to several microns for bacteria and bacterial spores, can be visualized by AFM under physiological conditions to a resolution of {approx}20-30 {angstrom}. We have also demonstrated that viruses from closely related families could be differentiated by AFM on

  2. Statistical analysis of atom probe data: Detecting the early stages of solute clustering and/or co-segregation

    International Nuclear Information System (INIS)

    Statistical analysis of atom probe data has improved dramatically in the last decade and it is now possible to determine the size, the number density and the composition of individual clusters or precipitates such as those formed in reactor pressure vessel (RPV) steels during irradiation. However, the characterisation of the onset of clustering or co-segregation is more difficult and has traditionally focused on the use of composition frequency distributions (for detecting clustering) and contingency tables (for detecting co-segregation). In this work, the authors investigate the possibility of directly examining the neighbourhood of each individual solute atom as a means of identifying the onset of solute clustering and/or co-segregation. The methodology involves comparing the mean observed composition around a particular type of solute with that expected from the overall composition of the material. The methodology has been applied to atom probe data obtained from several irradiated RPV steels. The results show that the new approach is more sensitive to fine scale clustering and co-segregation than that achievable using composition frequency distribution and contingency table analyses.

  3. Characterization of dilute optical lattices using pump-probe spectroscopy and photon correlation measurements

    Science.gov (United States)

    Clements, Ethan; Ross, Preston; Rapp, Anthony; Cai, Hong; Reigle, Alex; Schlonsky, Eli; Lee, Hoseong; Clemens, James; Bali, Samir

    2016-05-01

    We experimentally investigate optical lattices using three different methods: pump-probe spectroscopy of vibrational energy levels, photon correlation of light scattered by cold atoms, and fluorescence imaging. Photon correlations of the scattered light can be used to measure lattice dwell times and crossover times between lattice sites. From this information we can derive the diffusion constant which can then be compared to direct measurement via fluorescence imaging. Furthermore, by Fourier transforming the time delayed photon correlations we can obtain the intensity spectrum which can be compared directly to pump-probe spectroscopy of the vibrational energy levels. We plan to carefully study situations in which the atomic transport properties deviate from Boltzman Gibbs statistics.

  4. Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100 at 5 K: Probing the probe

    Directory of Open Access Journals (Sweden)

    Adam Sweetman

    2012-01-01

    Full Text Available Background: Noncontact atomic force microscopy (NC-AFM now regularly produces atomic-resolution images on a wide range of surfaces, and has demonstrated the capability for atomic manipulation solely using chemical forces. Nonetheless, the role of the tip apex in both imaging and manipulation remains poorly understood and is an active area of research both experimentally and theoretically. Recent work employing specially functionalised tips has provided additional impetus to elucidating the role of the tip apex in the observed contrast.Results: We present an analysis of the influence of the tip apex during imaging of the Si(100 substrate in ultra-high vacuum (UHV at 5 K using a qPlus sensor for noncontact atomic force microscopy (NC-AFM. Data demonstrating stable imaging with a range of tip apexes, each with a characteristic imaging signature, have been acquired. By imaging at close to zero applied bias we eliminate the influence of tunnel current on the force between tip and surface, and also the tunnel-current-induced excitation of silicon dimers, which is a key issue in scanning probe studies of Si(100.Conclusion: A wide range of novel imaging mechanisms are demonstrated on the Si(100 surface, which can only be explained by variations in the precise structural configuration at the apex of the tip. Such images provide a valuable resource for theoreticians working on the development of realistic tip structures for NC-AFM simulations. Force spectroscopy measurements show that the tip termination critically affects both the short-range force and dissipated energy.

  5. Comprehensive, atomic-level characterization of structurally characterized protein-protein interactions: the PICCOLO database

    Directory of Open Access Journals (Sweden)

    Bickerton George R

    2011-07-01

    Full Text Available Abstract Background Structural studies are increasingly providing huge amounts of information on multi-protein assemblies. Although a complete understanding of cellular processes will be dependent on an explicit characterization of the intermolecular interactions that underlie these assemblies and mediate molecular recognition, these are not well described by standard representations. Results Here we present PICCOLO, a comprehensive relational database capturing the details of structurally characterized protein-protein interactions. Interactions are described at the level of interacting pairs of atoms, residues and polypeptide chains, with the physico-chemical nature of the interactions being characterized. Distance and angle terms are used to distinguish 12 different interaction types, including van der Waals contacts, hydrogen bonds and hydrophobic contacts. The explicit aim of PICCOLO is to underpin large-scale analyses of the properties of protein-protein interfaces. This is exemplified by an analysis of residue propensity and interface contact preferences derived from a much larger data set than previously reported. However, PICCOLO also supports detailed inspection of particular systems of interest. Conclusions The current PICCOLO database comprises more than 260 million interacting atom pairs from 38,202 protein complexes. A web interface for the database is available at http://www-cryst.bioc.cam.ac.uk/piccolo.

  6. Nanopatterning on silicon surface using atomic force microscopy with diamond-like carbon (DLC-coated Si probe

    Directory of Open Access Journals (Sweden)

    Zhou Jingfang

    2011-01-01

    Full Text Available Abstract Atomic force microscope (AFM equipped with diamond-like carbon (DLC-coated Si probe has been used for scratch nanolithography on Si surfaces. The effect of scratch direction, applied tip force, scratch speed, and number of scratches on the size of the scratched geometry has been investigated. The size of the groove differs with scratch direction, which increases with the applied tip force and number of scratches but decreases slightly with scratch speed. Complex nanostructures of arrays of parallel lines and square arrays are further fabricated uniformly and precisely on Si substrates at relatively high scratch speed. DLC-coated Si probe has the potential to be an alternative in AFM-based scratch nanofabrication on hard surfaces.

  7. Cross-Sectional Investigations on Epitaxial Silicon Solar Cells by Kelvin and Conducting Probe Atomic Force Microscopy: Effect of Illumination.

    Science.gov (United States)

    Narchi, Paul; Alvarez, Jose; Chrétien, Pascal; Picardi, Gennaro; Cariou, Romain; Foldyna, Martin; Prod'homme, Patricia; Kleider, Jean-Paul; I Cabarrocas, Pere Roca

    2016-12-01

    Both surface photovoltage and photocurrent enable to assess the effect of visible light illumination on the electrical behavior of a solar cell. We report on photovoltage and photocurrent measurements with nanometer scale resolution performed on the cross section of an epitaxial crystalline silicon solar cell, using respectively Kelvin probe force microscopy and conducting probe atomic force microscopy. Even though two different setups are used, the scans were performed on locations within 100-μm distance in order to compare data from the same area and provide a consistent interpretation. In both measurements, modifications under illumination are observed in accordance with the theory of PIN junctions. Moreover, an unintentional doping during the deposition of the epitaxial silicon intrinsic layer in the solar cell is suggested from the comparison between photovoltage and photocurrent measurements. PMID:26831693

  8. Photoelectron imaging, probe of the dynamics: from atoms... to clusters; Imagerie de photoelectrons, sonde de la dynamique: des atomes... aux agregats

    Energy Technology Data Exchange (ETDEWEB)

    Lepine, F

    2003-06-15

    This thesis concerns the study of the deexcitation of clusters and atoms by photoelectron imaging. The first part is dedicated to thermionic emission of a finite size system. A 3-dimensional imaging setup allows us to measure the time evolution of the kinetic energy spectrum of electrons emitted from different clusters (W{sub n}{sup -}, C{sub n}{sup -}, C{sub 60}). Then we have a direct access to the fundamental quantities which characterize this statistical emission: the temperature of the finite heat bath and the decay rate. The second part concerns the ionization of atomic Rydberg states placed in a static electric field. We performed the first experiment of photoionization microscopy which allows us to obtain a picture which is the macroscopic projection of the electronic wave function. Then we have access to the detail of the photoionization and particularly to the quantum properties of the electron usually confined at the atomic scale. (author)

  9. Characterization of CdTe/CdSe quantum dots-transferrin fluorescent probes for cellular labeling

    Energy Technology Data Exchange (ETDEWEB)

    Guan Liyun; Li Yongqiang; Lin Song; Zhang Mingzhen; Chen Jun; Ma Zhiya [Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Department of Biomedical Engineering, Wuhan, HuBei 430074 (China); Zhao Yuandi, E-mail: zydi@mail.hust.edu.cn [Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Department of Biomedical Engineering, Wuhan, HuBei 430074 (China)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer A convenient method was designed to assess cell efficiency of QDs probes for cellular labeling. Black-Right-Pointing-Pointer The relationship between conjugation methods and effectiveness was evaluated clearly. Black-Right-Pointing-Pointer QDs-Tf probe synthesized by EDC coupling had the highest labeling efficiency, followed by electrostatic interaction, and dTf coating. - Abstract: In this paper, we prepared three types of transferrin-quantum dots conjugates (QDs-Tf) using three different methods (electrostatic interaction, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) coupling, denatured transferrin (dTf) coating). Fluorescence emission spectra, surface characteristics, zeta potentials of quantum dots (QDs) and QDs-Tf fluorescent probes were characterized by spectrophotometer, capillary electrophoresis, and dynamic light scattering. Fluorescent imaging of HeLa cells was also performed by QDs and QDs-Tf fluorescent probes. It was found that the fluorescence imaging performances of QDs-Tf probes prepared by electrostatic interaction and EDC coupling were better compared with the one prepared by dTf coating. Then a real-time single cell detection system was established to quantitatively evaluate cell labeling effects of QDs-Tf fluorescent probes. It was found that for cell labeling efficiency, the proportion of cells labeled by quantum dot probes to a group of cells, QDs-Tf probe prepared by EDC coupling showed the highest labeling efficiency (85.55 {+-} 3.88%), followed by electrostatic interaction (78.86 {+-} 9.57%), and dTf coating showed the lowest (40.09 {+-} 10.2%). This efficiency order was confirmed by flow cytometry results. This study demonstrated the relationship between conjugation methods and the resultant QDs-Tf probes and provided a foundation for choosing appropriate QDs-Tf probes in cell labeling.

  10. Characterization of CdTe/CdSe quantum dots-transferrin fluorescent probes for cellular labeling

    International Nuclear Information System (INIS)

    Highlights: ► A convenient method was designed to assess cell efficiency of QDs probes for cellular labeling. ► The relationship between conjugation methods and effectiveness was evaluated clearly. ► QDs-Tf probe synthesized by EDC coupling had the highest labeling efficiency, followed by electrostatic interaction, and dTf coating. - Abstract: In this paper, we prepared three types of transferrin-quantum dots conjugates (QDs-Tf) using three different methods (electrostatic interaction, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) coupling, denatured transferrin (dTf) coating). Fluorescence emission spectra, surface characteristics, zeta potentials of quantum dots (QDs) and QDs-Tf fluorescent probes were characterized by spectrophotometer, capillary electrophoresis, and dynamic light scattering. Fluorescent imaging of HeLa cells was also performed by QDs and QDs-Tf fluorescent probes. It was found that the fluorescence imaging performances of QDs-Tf probes prepared by electrostatic interaction and EDC coupling were better compared with the one prepared by dTf coating. Then a real-time single cell detection system was established to quantitatively evaluate cell labeling effects of QDs-Tf fluorescent probes. It was found that for cell labeling efficiency, the proportion of cells labeled by quantum dot probes to a group of cells, QDs-Tf probe prepared by EDC coupling showed the highest labeling efficiency (85.55 ± 3.88%), followed by electrostatic interaction (78.86 ± 9.57%), and dTf coating showed the lowest (40.09 ± 10.2%). This efficiency order was confirmed by flow cytometry results. This study demonstrated the relationship between conjugation methods and the resultant QDs-Tf probes and provided a foundation for choosing appropriate QDs-Tf probes in cell labeling.

  11. The Optical Design and Characterization of the Microwave Anisotropy Probe

    CERN Document Server

    Page, L; Barnes, C; Bennett, C; Halpern, M; Hinshaw, G; Jarosik, N C; Kogut, A J; Limon, M; Meyer, S S; Spergel, D N; Tucker, G S; Wilkinson, D T; Wollack, E; Wright, E L

    2003-01-01

    The primary goal of the MAP satellite, now in orbit, is to make high fidelity polarization sensitive maps of the full sky in five frequency bands between 20 and 100 GHz. From these maps we will characterize the properties of the cosmic microwave background (CMB) anisotropy and Galactic and extragalactic emission on angular scales ranging from the effective beam size, <0.23 degree, to the full sky. MAP is a differential microwave radiometer. Two back-to-back shaped offset Gregorian telescopes feed two mirror symmetric arrays of ten corrugated feeds. We describe the prelaunch design and characterization of the optical system, compare the optical models to the measurements, and consider multiple possible sources of systematic error.

  12. Predoping effects of boron and phosphorous on arsenic diffusion along grain boundaries in polycrystalline silicon investigated by atom probe tomography

    Science.gov (United States)

    Takamizawa, Hisashi; Shimizu, Yasuo; Inoue, Koji; Nozawa, Yasuko; Toyama, Takeshi; Yano, Fumiko; Inoue, Masao; Nishida, Akio; Nagai, Yasuyoshi

    2016-10-01

    The effect of P or B predoping on As diffusion in polycrystalline Si was investigated by atom probe tomography. In all samples, a high concentration of As was found at grain boundaries, indicating that such boundaries are the main diffusion path. However, As grain-boundary diffusion was suppressed in the B-doped sample and enhanced in the P-doped sample. In a sample codoped with both P and B, As diffusion was somewhat enhanced, indicating competition between the effects of the two dopants. The results suggest that As grain-boundary diffusion can be controlled by varying the local concentration of P or B.

  13. Precipitate characterisation of an advanced high-strength low-alloy (HSLA) steel using atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Timokhina, I.B. [Department of Materials Engineering, Monash University, Vic 3800 (Australia)], E-mail: Ilana.Timokhina@eng.monash.edu.au; Hodgson, P.D. [Centre for Material and Fibre Innovation, Deakin University, Geelong, Vic 3217 (Australia); Ringer, S.P. [Australia Key Centre for Microscopy and Microanalysis, University of Sydney, NSW (Australia); Zheng, R.K. [Australia Key Centre for Microscopy and Microanalysis, University of Sydney, NSW (Australia); Pereloma, E.V. [Department of Materials Engineering, Monash University, Vic 3800 (Australia)

    2007-04-15

    The microstructure of an advanced high-strength low-alloy steel containing nanoscale Ti{sub 0.98}Mo{sub 0.02}C{sub 0.6} carbides formed along {gamma}/{alpha} interface was characterised using atom probe tomography. The average radius of particles was 2 {+-} 0.5 nm. In addition, the formation of C{sub 19}Cr{sub 7}Mo{sub 24} particles with average radius of 1.5 {+-} 0.3 nm was also observed.

  14. Sodium distribution in solar-grade Cu2ZnSnS4 layers using atom-probe tomographic technique

    Science.gov (United States)

    Tajima, Shin; Asahi, Ryoji; Isheim, Dieter; Seidman, David N.; Itoh, Tadayoshi; Ohishi, Kei-ichiro

    2015-11-01

    To investigate the effect of alkali doping on Cu2ZnSnS4 (CZTS) photovoltaic cells, we studied compositional distributions in CZTS layers using three-dimensional atom-probe tomography. The segregation of Na at a concentration of approximately 1 at. % was observed predominantly at CZTS grain boundaries. The concentration of Na in the interior of the CZTS grains was below the detection limit (approximately 40 ppm). Na ions may exist as sulfide compounds at CZTS grain boundaries, independent of the presence of oxygen.

  15. Variation of local atomic structure due to devitrification of Ni-Zr alloy thin films probed by EXAFS measurements

    Science.gov (United States)

    Bhattacharya, Debarati; Tiwari, Nidhi; Bhattacharyya, Dibyendu; Jha, S. N.; Basu, S.

    2016-05-01

    Thin film metallic glasses (TFMGs) exhibit properties superior to their bulk counterparts allowing them to be potentially useful in many practical applications. Apart from their technological interest, when converted to crystallized state (devitrification) TFMGs can also act as precursors for partially crystallized or fully crystallized forms. Such devitrified forms are attractive due to their novel structural and magnetic properties. The amorphous-to-crystalline transformation of co-sputtered Ni-Zr alloy thin films through annealing was studied using EXAFS (Extended X-ray Absorption Fine Structure) measurements. Investigation through an atomic probe gives a better insight into the local environment of the atomic species, rendering a deeper understanding of thermal evolution of such materials.

  16. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  17. Characterizing optical dipole trap via fluorescence of trapped cesium atoms

    Institute of Scientific and Technical Information of China (English)

    LIU; Tao; GENG; Tao; YAN; Shubin; LI; Gang; ZHANG; Jing; WANG; Junmin; PENG; Kunchi; ZHANG; Tiancai

    2006-01-01

    Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.

  18. Preparation of light-atom tips for scanning probe microscopy by explosive delamination

    OpenAIRE

    Hofmann, Thomas; Welker, Joachim; Giessibl, Franz J

    2010-01-01

    To obtain maximal resolution in scanning tunneling microscopy (STM) and atomic force microscopy, the size of the protruding tip orbital has to be minimized. Beryllium as tip material is a promising candidate for enhanced resolution because a beryllium atom has just four electrons, leading to a small covalent radius of only 96 pm. Besides that, beryllium is conductive and has a high elastic modulus, which is a necessity for a stable tip apex. However, beryllium tips that are prepared ex situ a...

  19. Quantitative analysis of doped/undoped ZnO nanomaterials using laser assisted atom probe tomography: Influence of the analysis parameters

    Energy Technology Data Exchange (ETDEWEB)

    Amirifar, Nooshin; Lardé, Rodrigue, E-mail: rodrigue.larde@univ-rouen.fr; Talbot, Etienne; Pareige, Philippe; Rigutti, Lorenzo; Mancini, Lorenzo; Houard, Jonathan; Castro, Celia [Groupe de Physique des Matériaux, UMR CNRS 6634, Université et INSA de Rouen, Avenue de l' Université, BP 12, 76801 Saint Etienne du Rouvray (France); Sallet, Vincent; Zehani, Emir; Hassani, Said; Sartel, Corine [Groupe d' étude de la Matière Condensée (GEMAC), CNRS Université de Versailles St Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex (France); Ziani, Ahmed; Portier, Xavier [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CEA-CNRS-ENSICAEN, Université de Caen, 14050 Caen (France)

    2015-12-07

    In the last decade, atom probe tomography has become a powerful tool to investigate semiconductor and insulator nanomaterials in microelectronics, spintronics, and optoelectronics. In this paper, we report an investigation of zinc oxide nanostructures using atom probe tomography. We observed that the chemical composition of zinc oxide is strongly dependent on the analysis parameters used for atom probe experiments. It was observed that at high laser pulse energies, the electric field at the specimen surface is strongly dependent on the crystallographic directions. This dependence leads to an inhomogeneous field evaporation of the surface atoms, resulting in unreliable measurements. We show that the laser pulse energy has to be well tuned to obtain reliable quantitative chemical composition measurements of undoped and doped ZnO nanomaterials.

  20. Quantitative analysis of doped/undoped ZnO nanomaterials using laser assisted atom probe tomography: Influence of the analysis parameters

    Science.gov (United States)

    Amirifar, Nooshin; Lardé, Rodrigue; Talbot, Etienne; Pareige, Philippe; Rigutti, Lorenzo; Mancini, Lorenzo; Houard, Jonathan; Castro, Celia; Sallet, Vincent; Zehani, Emir; Hassani, Said; Sartel, Corine; Ziani, Ahmed; Portier, Xavier

    2015-12-01

    In the last decade, atom probe tomography has become a powerful tool to investigate semiconductor and insulator nanomaterials in microelectronics, spintronics, and optoelectronics. In this paper, we report an investigation of zinc oxide nanostructures using atom probe tomography. We observed that the chemical composition of zinc oxide is strongly dependent on the analysis parameters used for atom probe experiments. It was observed that at high laser pulse energies, the electric field at the specimen surface is strongly dependent on the crystallographic directions. This dependence leads to an inhomogeneous field evaporation of the surface atoms, resulting in unreliable measurements. We show that the laser pulse energy has to be well tuned to obtain reliable quantitative chemical composition measurements of undoped and doped ZnO nanomaterials.

  1. Quantitative analysis of doped/undoped ZnO nanomaterials using laser assisted atom probe tomography: Influence of the analysis parameters

    International Nuclear Information System (INIS)

    In the last decade, atom probe tomography has become a powerful tool to investigate semiconductor and insulator nanomaterials in microelectronics, spintronics, and optoelectronics. In this paper, we report an investigation of zinc oxide nanostructures using atom probe tomography. We observed that the chemical composition of zinc oxide is strongly dependent on the analysis parameters used for atom probe experiments. It was observed that at high laser pulse energies, the electric field at the specimen surface is strongly dependent on the crystallographic directions. This dependence leads to an inhomogeneous field evaporation of the surface atoms, resulting in unreliable measurements. We show that the laser pulse energy has to be well tuned to obtain reliable quantitative chemical composition measurements of undoped and doped ZnO nanomaterials

  2. A Comment on "The Far Future of Exoplanet Direct Characterization" - the Case for Interstellar Space Probes

    OpenAIRE

    Crawford, Ian A.

    2010-01-01

    Following on from ideas presented in a recent paper by Schneider et al. (2010) on "The Far Future of Exoplanet Direct Characterization", I argue that they have exaggerated the technical obstacles to performing such 'direct characterization' by means of fast (order 0.1c) interstellar space probes. A brief summary of rapid interstellar spaceflight concepts that may be found in the literature is presented. I argue that the presence of interstellar dust grains, while certainly something which wil...

  3. The Design, Fabrication and Characterization of a Transparent Atom Chip

    Directory of Open Access Journals (Sweden)

    Ho-Chiao Chuang

    2014-06-01

    Full Text Available This study describes the design and fabrication of transparent atom chips for atomic physics experiments. A fabrication process was developed to define the wire patterns on a transparent glass substrate to create the desired magnetic field for atom trapping experiments. An area on the chip was reserved for the optical access, so that the laser light can penetrate directly through the glass substrate for the laser cooling process. Furthermore, since the thermal conductivity of the glass substrate is poorer than other common materials for atom chip substrate, for example silicon, silicon carbide, aluminum nitride. Thus, heat dissipation copper blocks are designed on the front and back of the glass substrate to improve the electrical current conduction. The testing results showed that a maximum burnout current of 2 A was measured from the wire pattern (with a width of 100 μm and a height of 20 μm without any heat dissipation design and it can increase to 2.5 A with a heat dissipation design on the front side of the atom chips. Therefore, heat dissipation copper blocks were designed and fabricated on the back of the glass substrate just under the wire patterns which increases the maximum burnout current to 4.5 A. Moreover, a maximum burnout current of 6 A was achieved when the entire backside glass substrate was recessed and a thicker copper block was electroplated, which meets most requirements of atomic physics experiments.

  4. Electrostatic simulations of a local electrode atom probe: The dependence of tomographic reconstruction parameters on specimen and microscope geometry

    Energy Technology Data Exchange (ETDEWEB)

    Loi, Shyeh Tjing, E-mail: sloi5113@uni.sydney.edu.au [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); Gault, Baptiste, E-mail: gaultb@mcmaster.ca [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); Department of Materials Science and Engineering, McMaster University, 1280 Main St W, Hamilton, Ontario, Canada L8S4L8 (Canada); Ringer, Simon P. [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Larson, David J.; Geiser, Brian P. [Cameca Instruments Inc., 5500 Nobel Drive, Madison, WI 53711 (United States)

    2013-09-15

    We electrostatically model a local electrode atom probe microscope using the commercial software IES LORENTZ 2D v9.0 to investigate factors affecting the reconstruction parameters. We find strong dependences on the specimen geometry and voltage, and moderate dependences on the tip-aperture separation, which confirm that the current approach to atom probe reconstruction overlooks too many factors. Based on our data, which are in excellent agreement with known trends and experimental results, we derive a set of empirical relations which predict the values of the reconstruction parameters. These may be used to advance current reconstruction protocols by enabling the parameters to be adjusted as the specimen geometry changes. - Highlights: ► We perform electrostatic modelling of a LEAP for wires, microtips, and nanowires. ► Reconstruction parameters depend strongly on specimen geometry. ► The chamber has a non-zero-field and specimen/MCP voltages affect ion trajectories. ► k{sub f} is cubically related to ξ as previously shown. ► Derived empirical relations predict values in excellent agreement with experiment.

  5. Probing Magnetism in 2D Molecular Networks after in Situ Metalation by Transition Metal Atoms.

    Science.gov (United States)

    Schouteden, K; Ivanova, Ts; Li, Z; Iancu, V; Janssens, E; Van Haesendonck, C

    2015-03-19

    Metalated molecules are the ideal building blocks for the bottom-up fabrication of, e.g., two-dimensional arrays of magnetic particles for spintronics applications. Compared to chemical synthesis, metalation after network formation by an atom beam can yield a higher degree of control and flexibility and allows for mixing of different types of magnetic atoms. We report on successful metalation of tetrapyridyl-porphyrins (TPyP) by Co and Cr atoms, as demonstrated by scanning tunneling microscopy experiments. For the metalation, large periodic networks formed by the TPyP molecules on a Ag(111) substrate are exposed in situ to an atom beam. Voltage-induced dehydrogenation experiments support the conclusion that the porphyrin macrocycle of the TPyP molecule incorporates one transition metal atom. The newly synthesized Co-TPyP and Cr-TPyP complexes exhibit striking differences in their electronic behavior, leading to a magnetic character for Cr-TPyP only as evidenced by Kondo resonance measurements.

  6. The response of a neutral atom to a strong laser field probed by transient absorption near the ionisation threshold

    CERN Document Server

    Simpson, E R; Austin, D R; Diveki, Z; Hutchinson, S E E; Siegel, T; Ruberti, M; Averbukh, V; Miseikis, L; Strüber, C; Chipperfield, L; Marangos, J P

    2015-01-01

    We present transient absorption spectra of an extreme ultraviolet attosecond pulse train in helium dressed by an 800 nm laser field with intensity ranging from $2\\times10^{12}$ W/cm$^2$ to $2\\times10^{14}$ W/cm$^2$. The energy range probed spans 16-42 eV, straddling the first ionisation energy of helium (24.59 eV). By changing the relative polarisation of the dressing field with respect to the attosecond pulse train polarisation we observe a large change in the modulation of the absorption reflecting the vectorial response to the dressing field. With parallel polarized dressing and probing fields, we observe significant modulations with periods of one half and one quarter of the dressing field period. With perpendicularly polarized dressing and probing fields, the modulations of the harmonics above the ionisation threshold are significantly suppressed. A full-dimensionality solution of the single-atom time-dependent Schr\\"odinger equation obtained using the recently developed ab-initio time-dependent B-spline...

  7. Probing 2D Quantum Turbulence in Atomic Superfluid Gas using Bragg Scattering

    CERN Document Server

    Seo, Sang Won; Kim, Joon Hyun; Shin, Yong-il

    2016-01-01

    We demonstrate the use of spatially resolved Bragg spectroscopy for detection of the quantum vortex circulation signs in an atomic Bose-Einstein condensate (BEC). High-velocity atoms near the vortex cores are resonantly scattered from the BEC, and the vortex signs are determined from the scattered atom positions relative to the corresponding vortex cores. Using this method, we investigate decaying 2D quantum turbulence in a highly oblate BEC at temperatures of $\\sim 0.5 T_c$, where $T_c$ is the critical temperature of the trapped sample. Clustering of like-sign vortices is not observed; rather, the measured vortex configurations reveal weak pair correlations between the vortices and antivortices in the turbulent BEC. Our Bragg scattering method enables a direct experimental study of 2D quantum turbulence in BECs.

  8. Volatile organic compound ratios as probes of halogen atom chemistry in the Arctic

    Directory of Open Access Journals (Sweden)

    P. B. Shepson

    2008-03-01

    Full Text Available Volatile organic compound concentration ratios can be used as indicators of halogen chemistry that occurs during ozone depletion events in the Arctic during spring. Here we use a combination of modeling and measurements of [acetone]/[propanal] as an indicator of bromine chemistry, and [isobutane]/[n-butane] and [methyl ethyl ketone]/[n-butane] are used to study the extent of chlorine chemistry during four ozone depletion events during the Polar Sunrise Experiment of 1995. Using a 0-D photochemistry model in which the input of halogen atoms is controlled and varied, the approximate ratio of [Br]/[Cl] can be estimated for each ozone depletion event. It is concluded that there must be an additional source of propanal (likely from the snowpack to correctly simulate the VOC chemistry of the Arctic, and further evidence that the ratio of Br atoms to Cl atoms can vary greatly during ozone depletion events is presented.

  9. Volatile organic compound ratios as probes of halogen atom chemistry in the Arctic

    Directory of Open Access Journals (Sweden)

    A. E. Cavender

    2007-08-01

    Full Text Available Volatile organic compound concentration ratios can be used as indicators of halogen chemistry that occurs during ozone depletion events in the Arctic during spring. Here we use a combination of modeling and measurements of [acetone]/[propanal] as an indicator of bromine chemistry, and [isobutane]/[n-butane] and [methyl ethyl ketone]/[n-butane] are used to study the extent of chlorine chemistry during four ozone depletion events during the Polar Sunrise Experiment of 1995. Using a 0-D photochemistry model in which the input of halogen atoms is controlled and varied, the approximate ratio of [Br]/[Cl] can be estimated for each ozone depletion event. It is concluded that there must be an additional source of propanal (likely from the snowpack to correctly simulate the VOC chemistry of the Arctic, and that the ratio of Br atoms to Cl atoms can vary greatly during ozone depletion events.

  10. X-ray absorption spectroscopy in electrical fields: An element-selective probe of atomic polarization

    Science.gov (United States)

    Ney, V.; Wilhelm, F.; Ollefs, K.; Rogalev, A.; Ney, A.

    2016-01-01

    We have studied a range of polar and nonpolar materials using x-ray absorption near-edge spectroscopy (XANES) in external electric fields. An energy shift of the XANES by a few meV/kV is found which scales linearly with the applied voltage, thus being reminiscent of the linear Stark effect. This is corroborated by the consistent presence of this energy shift in polar thin films and bulk crystals and its absence in nonpolar materials as well as in conducting films. The observed energy shift of the XANES is different between two atomic species in one specimen and appears to scale linearly with the atomic number of the studied element. Therefore, XANES in electrical fields opens the perspective to study atomic polarization with element specificity in a range of functional materials.

  11. Design and characterization of a novel multimodal fiber-optic probe and spectroscopy system for skin cancer applications

    OpenAIRE

    Sharma, Manu; Marple, Eric; Reichenberg, Jason; Tunnell, James W.

    2014-01-01

    The design and characterization of an instrument combining Raman, fluorescence, and reflectance spectroscopic modalities is presented. Instrument development has targeted skin cancer applications as a novel fiber-optic probe has been specially designed to interrogate cutaneous lesions. The instrument is modular and both its software and hardware components are described in depth. Characterization of the fiber-optic probe is also presented, which details the probe's ability to measure diagnost...

  12. Precision atomic beam density characterization by diode laser absorption spectroscopy

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10-5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 104 atoms cm-3. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  13. Grain boundary segregation in Fe–Mn–C twinning-induced plasticity steels studied by correlative electron backscatter diffraction and atom probe tomography

    International Nuclear Information System (INIS)

    We report on the characterization of grain boundary (GB) segregation in an Fe–28Mn–0.3C (wt.%) twinning-induced plasticity (TWIP) steel. After recrystallization of this steel for 24 h at 700 °C, ∼50% general grain boundaries (GBs) and ∼35% Σ3 annealing twin boundaries were observed (others were high-order Σ and low-angle GBs). The segregation of B, C and P and traces of Si and Cu were detected at the general GB by atom probe tomography (APT) and quantified using ladder diagrams. In the case of the Σ3 coherent annealing twin, it was necessary to first locate the position of the boundary by density analysis of the atom probe data, then small amounts of B, Si and P segregation and, surprisingly, depletion of C were detected. The concentration of Mn was constant across the interface for both boundary types. The depletion of C at the annealing twin is explained by a local change in the stacking sequence at the boundary, creating a local hexagonal close-packed structure with low C solubility. This finding raises the question of whether segregation/depletion also occurs at Σ3 deformation twin boundaries in high-Mn TWIP steels. Consequently, a previously published APT dataset of the Fe–22Mn–0.6C alloy system, containing a high density of deformation twins due to 30% tensile deformation at room temperature, was reinvestigated using the same analysis routine as for the annealing twin. Although crystallographically identical to the annealing twin, no evidence of segregation or depletion was found at the deformation twins, owing to the lack of mobility of solutes during twin formation at room temperature

  14. Probing Matter-Field and Atom-Number Correlations in Optical Lattices by Global Nondestructive Addressing

    CERN Document Server

    Kozlowski, Wojciech; Mekhov, Igor B

    2014-01-01

    We show that light scattering from an ultracold gas reveals not only density correlations, but also matter-field interference at its shortest possible distance in an optical lattice, which defines key properties such as tunneling and matter-field phase gradients. This signal can be enhanced by concentrating probe light between lattice sites rather than at density maxima. As addressing between two single sites is challenging, we focus on global nondestructive scattering, allowing probing order parameters, matter-field quadratures and their squeezing. The scattering angular distribution displays peaks even if classical diffraction is forbidden and we derive generalized Bragg conditions. Light scattering distinguishes all phases in the Mott insulator - superfluid - Bose glass phase transition.

  15. NATO Advanced Study Institute on Scanning Probe Microscopy : Characterization, Nanofabrication and Device Application of Functional Materials

    CERN Document Server

    Vilarinho, Paula Maria; Kingon, Angus; Scanning Probe Microscopy : Characterization, Nanofabrication and Device Application of Functional Materials

    2005-01-01

    As the characteristic dimensions of electronic devices continue to shrink, the ability to characterize their electronic properties at the nanometer scale has come to be of outstanding importance. In this sense, Scanning Probe Microscopy (SPM) is becoming an indispensable tool, playing a key role in nanoscience and nanotechnology. SPM is opening new opportunities to measure semiconductor electronic properties with unprecedented spatial resolution. SPM is being successfully applied for nanoscale characterization of ferroelectric thin films. In the area of functional molecular materials it is being used as a probe to contact molecular structures in order to characterize their electrical properties, as a manipulator to assemble nanoparticles and nanotubes into simple devices, and as a tool to pattern molecular nanostructures. This book provides in-depth information on new and emerging applications of SPM to the field of materials science, namely in the areas of characterisation, device application and nanofabrica...

  16. Probing the compressibility of tumor cell nuclei by combined atomic force-confocal microscopy

    NARCIS (Netherlands)

    Krause, M.; Riet, J. te; Wolf, K. van der

    2013-01-01

    The cell nucleus is the largest and stiffest organelle rendering it the limiting compartment during migration of invasive tumor cells through dense connective tissue. We here describe a combined atomic force microscopy (AFM)-confocal microscopy approach for measurement of bulk nuclear stiffness toge

  17. Perfect/complete scattering experiments. Probing quantum mechanics on atomic and molecular collisions and coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Lohmann, Bernd [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Grum-Grzhimailo, Alexei N. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Kleinpoppen, Hans

    2013-07-01

    Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is

  18. Perfect/complete scattering experiments. Probing quantum mechanics on atomic and molecular collisions and coincidences

    International Nuclear Information System (INIS)

    Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is, until today, hardly to perform

  19. Probing an Excited-State Atomic Transition Using Hyperfine Quantum Beat Spectroscopy

    CERN Document Server

    Wade, Christopher G; Keaveney, James; Adams, Charles S; Weatherill, Kevin J

    2014-01-01

    We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P$_{3/2}$ state to the 7S$_{1/2}$ state. We observe quantum beats in the fluorescence from the 6P$_{3/2}$ state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P$_{3/2}$, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved.

  20. Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system

    Science.gov (United States)

    Kato, Shinya; Inaba, Kensuke; Sugawa, Seiji; Shibata, Kosuke; Yamamoto, Ryuta; Yamashita, Makoto; Takahashi, Yoshiro

    2016-04-01

    A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

  1. New possibilities in high sensitivity low energy ion scattering (LEIS) for probing the outermost atomic layer

    International Nuclear Information System (INIS)

    With a recently developed high sensitivity low energy ion scattering (LEIS) instrument, a range of new applications arises for this extremely surface sensitive analytical technique. Known capabilities of LEIS are the selective characterisation and quantification of the atomic composition of the outermost atomic layer, i. e. precisely the atoms that control properties like catalytic performance, adhesion, wetting, corrosion, etc. New possibilities such as surface imaging, sputter as well as non-destructive (static) profiling and even higher sensitivity for light elements have been added. The energy range of the primary ion source of up to 8 keV allows an improved mass resolution, thus enabling a better separation of the heaviest elements. In addition, a time-of-flight filter dramatically improves the detection limit for light elements. This filter suppresses the signal arising from sputtered ions, while scattered ions reach the detection system unhindered. In this contribution, we show the utilization of these new capabilities to a range of samples and applications. Furthermore, we will show how LEIS can benefit from the combination with the complementary technique time-of-flight secondary ion mass spectrometry (TOF-SIMS), which adds ppb-ppm sensitivity, lateral resolution of 100 nm and chemical information

  2. Design and implementation of precise position controller of active probe of atomic force microscopy for nanomanipulation

    Institute of Scientific and Technical Information of China (English)

    HAO LiNa; ZHANG JiangBo; XI Ning

    2008-01-01

    Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved,due to the nonlinearities and uncertainties,such as drift,creep,hysteresis,etc.The deformation of cantilevers caused by manipulation force is also one of the most major factors of nonlinearities and uncertainties.It causes difficulties in precise control of the tip position and causes the tip to miss the position of the object.In order to solve this problem,the traditional approach is to use a rigid cantilever.However,this will significantly reduce the sensitivity of force sensing during manipulation,which is essential for achieving an efficient and reliable nanomanipulation.In this paper,a kind of active AFM probe has been used to solve this problem by directly controlling the cantilever's flexibility or rigidity during manipu- lation.Based on Euller-Bernoulli Model,a kind of controller of the active probe employing Peri- odic-Output-Feedback (POF) law is implemented.The results of simulation and experiments have demonstrated that this theoretical model and POF controller are suitable for precise position control of nanomanipulation.

  3. Chemical gradients across phase boundaries between martensite and austenite in steel studied by atom probe tomography and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dmitrieva, O.; Ponge, D.; Inden, G.; Millan, J.; Choi, P. [Max-Planck-Institut fuer Eisenforschung, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Sietsma, J. [Delft University of Technology, Faculty 3mE, Dept. MSE, 2628 CD Delft (Netherlands); Raabe, D., E-mail: d.raabe@mpie.de [Max-Planck-Institut fuer Eisenforschung, Max-Planck-Str. 1, 40237 Duesseldorf (Germany)

    2011-01-15

    Partitioning at phase boundaries of complex steels is important for their properties. We present atom probe tomography results across martensite/austenite interfaces in a precipitation-hardened maraging-TRIP steel (12.2 Mn, 1.9 Ni, 0.6 Mo, 1.2 Ti, 0.3 Al; at.%). The system reveals compositional changes at the phase boundaries: Mn and Ni are enriched while Ti, Al, Mo and Fe are depleted. More specific, we observe up to 27 at.% Mn in a 20 nm layer at the phase boundary. This is explained by the large difference in diffusivity between martensite and austenite. The high diffusivity in martensite leads to a Mn flux towards the retained austenite. The low diffusivity in the austenite does not allow accommodation of this flux. Consequently, the austenite grows with a Mn composition given by local equilibrium. The interpretation is based on DICTRA and mixed-mode diffusion calculations (using a finite interface mobility).

  4. Analysis of modulus hardening in an artificial aged Al–Cu–Mg alloy by atom probe tomography

    International Nuclear Information System (INIS)

    The individual contribution of different Cu–Mg co-clusters by modulus hardening to age-hardening response of an Al–Cu–Mg alloy at 170 °C is evaluated based on Vickers hardness measurements and quantitative atom probe tomography analysis. The present results show that it is order hardening of large Cu-Mg co-clusters or GPB zones rather than modulus hardening significantly contributes to the second stage of hardening. Despite prolonged aging from 5 min to 8 h leads to a noticeable change in the number density and the volume fraction of different Cu-Mg co-clusters, interestingly, the total critical shear stress of Cu-Mg co-clusters by modulus hardening fluctuates slightly, indicating the modulus hardening effect almost keeps unchanged at the hardness plateau. Besides, the shear modulus of Cu-Mg co-clusters is found to remain constant as aging prolongs at 170 °C

  5. A novel atomic force microscope operating in liquid with open probe unit and optimized laser tracking system

    Institute of Scientific and Technical Information of China (English)

    Xia Fu; Dongxian Zhang; Haijun Zhang

    2009-01-01

    A novel atomic force microscope (AFM) for large samples to be measured in liquid is developed.An innovative laser beam tracking system is proposed to eliminate the tracking and feedback errors.The open probe design of the AFM makes the operation in liquid convenient and easy.A standard 1200-lines/mm grating and a sheet of filter paper are imaged respectively in air and liquid to confirm its performance.The corrosion behavior of aluminum surface in 1-mol/L NaOH solution is further investigated by the AFM.Experimental results show that the system can realize wide range (20 × 20 (μm)) scanning for large samples both in air and liquid,while keeping nanometer order resolution in liquid by eliminating the tracking and feedback error.

  6. Atom-probe tomographic study of interfaces of Cu{sub 2}ZnSnS{sub 4} photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, S., E-mail: e0954@mosk.tytlabs.co.jp; Asahi, R.; Itoh, T.; Hasegawa, M.; Ohishi, K. [Toyota Central R and D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Isheim, D.; Seidman, D. N. [Northwestern University, Evanston, Illinois 60208-3108 (United States)

    2014-09-01

    The heterophase interfaces between the CdS buffer layer and the Cu{sub 2}ZnSnS{sub 4} (CZTS) absorption layers are one of the main factors affecting photovoltaic performance of CZTS cells. We have studied the compositional distributions at heterophase interfaces in CZTS cells using three-dimensional atom-probe tomography. The results demonstrate: (a) diffusion of Cd into the CZTS layer; (b) segregation of Zn at the CdS/CZTS interface; and (c) a change of oxygen and hydrogen concentrations in the CdS layer depending on the heat treatment. Annealing at 573 K after deposition of CdS improves the photovoltaic properties of CZTS cells probably because of the formation of a heterophase epitaxial junction at the CdS/CZTS interface. Conversely, segregation of Zn at the CdS/CZTS interface after annealing at a higher temperature deteriorates the photovoltaic properties.

  7. Oxygen concentration of EuBa2Cu307-x in vacuum: an atom probe study II

    International Nuclear Information System (INIS)

    Atom Probe mass analysis using a wide acceptance angle instrument was used to measure the oxygen content and metallic stoichiometry of the near-surface region of the superconducting ceramic oxide EuBa2Cu307-x (x≅0.1) after exposure at 85K and room temperature in vacuum. An oxygen depleted layer formed by H2 imaging must be removed before bulk concentrations are obtained. Room temperature holding in vacuum overnight then depletes the surface of oxygen to a depth of greater than 4 layers (1.2 nm). However, after holding the specimen at 85K for up to 3h either with or without an applied field, no detectable loss of oxygen occurred. Therefore, for short time vacuum exposures at liquid nitrogen temperatures and below, no oxygen loss is expected, however, significant oxygen loss occurs for 18h vacuum exposures at room temperature

  8. Impact of Dynamic Specimen Shape Evolution on the Atom Probe Tomography Results of Doped Epitaxial Oxide Multilayers: Comparison of Experiment and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Madaan, Nitesh; Bao, Jie; Nandasiri, Manjula I.; Xu, Zhijie; Thevuthasan, Suntharampillai; Devaraj, Arun

    2015-08-31

    The experimental atom probe tomography results from two different specimen orientations (top-down and side-ways) of a high oxygen ion conducting Samaria-doped-ceria/Scandia-stabilized-zirconia multilayer thin film solid oxide fuel cell electrolyte was correlated with level-set method based field evaporation simulations for the same specimen orientations. This experiment-theory correlation explains the dynamic specimen shape evolution and ion trajectory aberrations that can induce density artifacts in final reconstruction leading to inaccurate estimation of interfacial intermixing. This study highlights the need and importance of correlating experimental results with field evaporation simulations when using atom probe tomography for studying oxide heterostructure interfaces.

  9. Nano-scale mechanical probing of supported lipid bilayers with atomic force microscopy

    OpenAIRE

    Das, Chinmay; Sheik, Khizar H.; Olmsted, Peter D.; Connell, Simon D.

    2010-01-01

    We present theory and experiments for the force-distance curve $F(z_0)$ of an atomic force microscope (AFM) tip (radius $R$) indenting a supported fluid bilayer (thickness $2d$). For realistic conditions the force is dominated by the area compressibility modulus $\\kappa_A$ of the bilayer, and, to an excellent approximation, given by $F= \\pi \\kappa_A R z_0^2/(2d-z_0)^2$. The experimental AFM force curves from coexisting liquid ordered and liquid disordered domains in 3-component lipid bilayers...

  10. Alignment dependence of photoelectron momentum distributions of atomic and molecular targets probed by few-cycle circularly polarized laser pulses

    Science.gov (United States)

    Abu-samha, M.; Madsen, Lars Bojer

    2016-08-01

    We present theoretical photoelectron momentum distributions (PMDs) for ionization from Ar(3 p ) and H2+ (σg) orbitals by few-cycle, high-intensity, near-infrared laser fields circularly polarized in the x y plane. The three-dimensional time-dependent Schrödinger equation is solved numerically within the single-active-electron approximation for Ar and within the fixed nuclei approximation for H2+ . The PMDs are investigated for alignment of the probed target orbitals relative to the polarization plane of the laser field. In the atomic case, the PMDs in the polarization plane for aligned 3 p Ar orbitals are, up to an overall scaling factor, insensitive to alignment of the probed orbital, while the lateral PMDs show a signature of the orbital node when that node is sufficiently close to the polarization plane. For the molecular case of H2+ (σg), our results show a significant impact of alignment on the PMDs due to the anisotropic molecular potential and the alignment-dependent coupling between the ground state and excited states.

  11. Structurally Well-Defined Sigmoidal Gold Clusters: Probing the Correlation between Metal Atom Arrangement and Chiroptical Response.

    Science.gov (United States)

    He, Xin; Wang, Yuechao; Jiang, Hong; Zhao, Liang

    2016-05-01

    Asymmetric arrangement of metal atoms is crucial for understanding the chirality origin of chiral metal nanoclusters and facilitating the design and development of new chiral catalysts and chiroptical devices. Here, we describe the construction of four asymmetric gold and gold-silver clusters by chirality transfer from diimido ligands. The acquired metal clusters show strong circular dichroism (CD) response with large anisotropy factors of up to 6 × 10(-3), larger than the values of most reported chiral gold nanoclusters. Regardless of the same absolute configuration of the applied three diimido ligands, sigmoidal and reverse-sigmoidal arrangements of gold atoms both can be achieved, which resultantly produce an opposite Cotton effect within a specific absorption range. On the basis of the detailed structural characterization via X-ray crystallography and contrast experiments, the chirality contribution of the imido ligand, the asymmetrically arranged metal cluster, and the chiral arrangement of aromatic rings of phosphine ligands have been qualitatively evaluated. Time-dependent DFT calculations reveal that the chiroptical property of the acquired metal clusters is mainly influenced by the asymmetrically arranged metal atoms. Correlation of asymmetric arrangements of metal atoms in clusters with their chiroptical response provides a viable means of fabricating a designable chiral surface of metal nanoclusters and opens a broader prospect for chiral cluster application.

  12. Probes for 4th generation constituents of dark atoms in Higgs boson studies at the LHC

    CERN Document Server

    Khlopov, M Yu

    2014-01-01

    The nonbaryonic dark matter of the Universe can consist of new stable charged species, bound in heavy neutral "atoms" by ordinary Coulomb interaction. Stable $\\bar U$ (anti-$U$)quarks of 4th generation, bound in stable colorless ($\\bar U \\bar U \\bar U $) clusters, are captured by the primordial helium, produced in Big Bang Nucleosynthesis, thus forming neutral "atoms" of O-helium (OHe), a specific nuclear interacting dark matter that can provide solution for the puzzles of direct dark matter searches. However, the existence of the 4th generation quarks and leptons should influence the production and decay rates of Higgs boson and is ruled out by the experimental results of the Higgs boson searches at the LHC, if the Higgs boson coupling to 4th generation fermions with is not suppressed. Here we argue that the difference between the three known quark-lepton families and the 4th family can naturally lead to suppression of this coupling, relating the accelerator test for such a composite dark matter scenario to ...

  13. Atom probe analysis on interaction between Cr and N in bake-hardening steels with anti-aging properties at RT

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Jun, E-mail: takahashi.3ct.jun@jp.nssmc.com [Advanced Technology Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, 20-1, Shintomi, Futtsu-city, Chiba 293-8511 (Japan); Maruyama, Naoki; Kawakami, Kazuto; Yoshinaga, Naoki; Sugiyama, Masaaki [Advanced Technology Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, 20-1, Shintomi, Futtsu-city, Chiba 293-8511 (Japan); Ohkubo, Tadakatsu; Ping, De-hai; Hono, Kazuhiro [National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2013-11-15

    One-dimensional atom probe (1DAP) analysis was performed on chromium and nitrogen added bake hardening steel sheets that have both high bake-hardenability and anti-aging properties at room temperature (RT). The atomic data of more than 2 million atoms were collected for sample steels with and without low-temperature aging after recrystallization annealing and quenching. The correlation in atomic position between chromium and nitrogen atoms in a solid solution was investigated by a statistical analysis using the binomial distribution function. In the samples with low-temperature aging, the probability that a chromium atom was observed near a nitrogen atom was significantly higher than that estimated from the null hypothesis that there was no attractive atomic interaction. This suggests that there is an attractive interaction between a nitrogen atom and a chromium atom in bcc iron, which led to the anti-aging properties at RT. In contrast, such correlation was not observed definitely in the samples without low-temperature aging, which implied that the atomic pair formation is a thermal activation process.

  14. Oxidized carbon nitrides: water-dispersible, atomically thin carbon nitride-based nanodots and their performances as bioimaging probes.

    Science.gov (United States)

    Oh, Junghoon; Yoo, Ran Ji; Kim, Seung Yeon; Lee, Yong Jin; Kim, Dong Wook; Park, Sungjin

    2015-04-13

    Three-dimensional (3D) carbon nitride (C3 N4 )-based materials show excellent performance in a wide range of applications because of their suitable band structures. To realize the great promise of two-dimensional (2D) allotropes of various 3D materials, it is highly important to develop routes for the production of 2D C3 N4 materials, which are one-atom thick, in order to understand their intrinsic properties and identify their possible applications. In this work, water-dispersible, atomically thin, and small carbon nitride nanodots were produced using the chemical oxidation of graphitic C3 N4 . Various analyses, including X-ray diffraction, X-ray photoelectron, Fourier-transform infrared spectroscopy, and combustion-based elemental analysis, and thermogravimetric analysis, confirmed the production of 3D oxidized C3 N4 materials. The 2D C3 N4 nanodots were successfully exfoliated as individual single layers; their lateral dimension was several tens of nanometers. They showed strong photoluminescence in the visible region as well as excellent performances as cell-imaging probes in an in vitro study using confocal fluorescence microscopy.

  15. Broadband Rydberg Atom-Based Electric-Field Probe: From Self-Calibrated Measurements to Sub-Wavelength Imaging

    CERN Document Server

    Holloway, Christopher L; Jefferts, Steven; Schwarzkopf, Andrew; Anderson, David A; Miller, Stephanie A; Thaicharoen, Nithiwadee; Raithel, Georg

    2014-01-01

    We discuss a fundamentally new approach for the measurement of electric (E) fields that will lead to the development of a broadband, direct SI-traceable, compact, self-calibrating E-field probe (sensor). This approach is based on the interaction of radio frequency (RF) fields with alkali atoms excited to Rydberg states. The RF field causes an energy splitting of the Rydberg states via the Autler-Townes effect and we detect the splitting via electromagnetically induced transparency (EIT). In effect, alkali atoms placed in a vapor cell act like an RF-to-optical transducer, converting an RF E-field strength measurement to an optical frequency measurement. We demonstrate the broadband nature of this approach by showing that one small vapor cell can be used to measure E-field strengths over a wide range of frequencies: 1 GHz to 500 GHz. The technique is validated by comparing experimental data to both numerical simulations and far-field calculations for various frequencies. We also discuss various applications, in...

  16. Characterization of anomalous Zeeman patterns in complex atomic spectra

    CERN Document Server

    Pain, Jean-Christophe

    2012-01-01

    The modeling of complex atomic spectra is a difficult task, due to the huge number of levels and lines involved. In the presence of a magnetic field, the computation becomes even more difficult. The anomalous Zeeman pattern is a superposition of many absorption or emission profiles with different Zeeman relative strengths, shifts, widths, asymmetries and sharpnesses. We propose a statistical approach to study the effect of a magnetic field on the broadening of spectral lines and transition arrays in atomic spectra. In this model, the sigma and pi profiles are described using the moments of the Zeeman components, which depend on quantum numbers and Land\\'{e} factors. A graphical calculation of these moments, together with a statistical modeling of Zeeman profiles as expansions in terms of Hermite polynomials are presented. It is shown that the procedure is more efficient, in terms of convergence and validity range, than the Taylor-series expansion in powers of the magnetic field which was suggested in the past...

  17. Characterization of fan spray atomizers through numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Altimira, Mireia [Thermal and Fluids Engineering Division, Mechanical Engineering Department, Tecnun (University of Navarra), Manuel de Lardizabal 13, 20018 San Sebastian (Spain)], E-mail: maltimira@tecnun.es; Rivas, Alejandro; Larraona, Gorka S.; Anton, Raul; Ramos, Juan Carlos [Thermal and Fluids Engineering Division, Mechanical Engineering Department, Tecnun (University of Navarra), Manuel de Lardizabal 13, 20018 San Sebastian (Spain)

    2009-04-15

    The present paper focuses on the mathematical modeling of industrial fan spray atomizers. The two-phase flow taking place inside the nozzle's tip and the exterior region near the outlet of three different industrial nozzle designs has been modeled and simulated. As a result, valuable information has been obtained regarding the influence of the inner geometry on the flow and also the formation and development of the liquid sheet. Characteristic magnitudes such as the discharge coefficient and the liquid sheet thickness factor have been obtained and validated through experimental measurements. The accumulation of liquid at the border of fan-shaped liquid sheets, also known as rim, has been studied in the analyzed designs, revealing the presence of a tangential velocity component in the liquid sheet and a relationship between the incoming flow rate of the rim and the angle of the liquid sheet. The dependence of the results on turbulence modeling has also been analyzed, drawing interesting conclusions regarding their influence on the liquid sheet mean flow characteristics and on the surrounding gas. Thus, the mathematical model developed has been proved to be a useful tool for nozzle manufacturers; it provides the most important characteristic parameters of the liquid sheet formed given certain nozzle geometry and, additionally, those data necessary to carry out studies of instability, breakup and atomization of the liquid sheet.

  18. Atom probe analysis of early-stage strengthening behaviour in an Al-Mg-Si-Cu alloy

    International Nuclear Information System (INIS)

    The strengthening of an Al-Mg-Si-Cu alloy during natural ageing and subsequent short artificial ageing was investigated using three-dimensional atom probe (3DAP) analysis and tensile testing. The contingency table and Markov chain analyses confirmed that non-random arrangements of atoms already exist after a natural ageing time of only 3.5 h. Extensive use of particle analysis tools in the IVAS and PoSAP software packages revealed that whilst the commonly used minimum aggregate size (Nmin) of 10 is a reasonable choice, much more useful information about the system can be gained by additionally employing a wide range of larger and smaller Nmin values. In particular, it was found that the density and volume fraction of solute aggregates increased with increasing natural ageing time in the T4 condition. After a 0.5 h artificial ageing treatment at 170 oC (designated as T6), the size, volume fraction and Mg/Si ratio of the aggregates were all found to decrease with increasing prior natural ageing time. These findings are used to discuss the detrimental effect of natural ageing, where the T6 strength has been observed to decrease rapidly with increasing prior natural ageing time before stabilising after several hours of natural ageing. -- Research Highlights: → The ageing response at 170 oC is reduced by 100 MPa after >3 h of natural ageing. → Non-random arrangements of atoms exist after 3.5 h of natural ageing. → Analysis of 3DAP data is enhanced by systematically varying Nmin values. → T4 strength is related to the density and volume fraction of small solute aggregates. → T6 strength is related to the size, volume fraction and Mg/Si ratio of aggregates.

  19. Atom probe tomography study of internal interfaces in Cu2ZnSnSe4 thin-films

    Science.gov (United States)

    Schwarz, T.; Cojocaru-Mirédin, O.; Choi, P.; Mousel, M.; Redinger, A.; Siebentritt, S.; Raabe, D.

    2015-09-01

    We report on atom probe tomography studies of the composition at internal interfaces in Cu2ZnSnSe4 thin-films. For Cu2ZnSnSe4 precursors, which are deposited at 320 °C under Zn-rich conditions, grain boundaries are found to be enriched with Cu irrespective of whether Cu-poor or Cu-rich growth conditions are chosen. Cu2ZnSnSe4 grains are found to be Cu-poor and excess Cu atoms are found to be accumulated at grain boundaries. In addition, nanometer-sized ZnSe grains are detected at or near grain boundaries. The compositions at grain boundaries show different trends after annealing at 500 °C. Grain boundaries in the annealed absorber films, which are free of impurities, are Cu-, Sn-, and Se-depleted and Zn-enriched. This is attributed to dissolution of ZnSe at the Cu-enriched grain boundaries during annealing. Furthermore, some of the grain boundaries of the absorbers are enriched with Na and K atoms, stemming from the soda-lime glass substrate. Such grain boundaries show no or only small changes in composition of the matrix elements. Na and K impurities are also partly segregated at some of the Cu2ZnSnSe4/ZnSe interfaces in the absorber, whereas for the precursors, only Na was detected at such phase boundaries possibly due to a higher diffusivity of Na compared to K. Possible effects of the detected compositional fluctuations on cell performance are discussed.

  20. Probing intra-molecular mechanics of single circularly permuted green fluorescent protein with atomic force microscopy

    International Nuclear Information System (INIS)

    We investigated the mechanical unfolding of single circularly permuted green fluorescent protein (cpGFP) with atomic force microscopy (AFM). The molecule was stretched from its N- and C-termini by an external force causing an elongation of the polypeptide chain up to its full length. The features of the force-extension (F-E) curves were found to depend on the stretching speed. At fast speeds, we detected one peak in the F-E curves before final rupture of the extended molecule, which we interpreted as the unfolding of two terminal halves within cpGFP. We observed several more force peaks in a sawtooth pattern at much slower speeds, and explained the appearance of such force peaks as cooperative unfolding of the hidden sub-structures inside each terminal half

  1. Nanoscale mechanical probing of supported lipid bilayers with atomic force microscopy.

    Science.gov (United States)

    Das, Chinmay; Sheikh, Khizar H; Olmsted, Peter D; Connell, Simon D

    2010-10-01

    We present theory and experiments for the force-distance curve F(z(0)) of an atomic force microscope (AFM) tip (radius R) indenting a supported fluid bilayer (thickness 2d). For realistic conditions the force is dominated by the area compressibility modulus κ(A) of the bilayer and, to an excellent approximation, given by F=πκ(A)Rz(0)(2)/(2d-z(0))(2). The experimental AFM force curves from coexisting liquid ordered and liquid disordered domains in three-component lipid bilayers are well described by our model, which provides κ(A) in agreement with literature values. The liquid ordered phase has a yieldlike response that we model as due to the breaking of hydrogen bonds. PMID:21230326

  2. Effect of Alginate Lyase on Biofilm-Grown Helicobacter pylori Probed by Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Alessandro Maiorana

    2015-01-01

    Full Text Available Helicobacter pylori (H. pylori is a microorganism with a pronounced capability of adaptation under environmental stress solicitations. Its persistence and antimicrobial resistance to the drugs commonly used in the anti-H. pylori therapy are associated with the development of a biofilm mainly composed of DNA, proteins, and polysaccharides. A fundamental step to increase the success of clinical treatments is the development of new strategies and molecules able to interfere with the biofilm architecture and thus able to enhance the effects of antibiotics. By using Atomic Force Microscopy and Scanning Electron Microscopy we analyzed the effects of the alginate lyase (AlgL, an enzyme able to degrade a wide class of polysaccharides, on the H. pylori shape, surface morphology, and biofilm adhesion properties. We demonstrated that AlgL generates a noticeable loss of H. pylori coccoid form in favor of the bacillary form and reduces the H. pylori extracellular polymeric substances (EPS.

  3. Nano-scale mechanical probing of supported lipid bilayers with atomic force microscopy

    CERN Document Server

    Das, Chinmay; Olmsted, Peter D; Connell, Simon D

    2010-01-01

    We present theory and experiments for the force-distance curve $F(z_0)$ of an atomic force microscope (AFM) tip (radius $R$) indenting a supported fluid bilayer (thickness $2d$). For realistic conditions the force is dominated by the area compressibility modulus $\\kappa_A$ of the bilayer, and, to an excellent approximation, given by $F= \\pi \\kappa_A R z_0^2/(2d-z_0)^2$. The experimental AFM force curves from coexisting liquid ordered and liquid disordered domains in 3-component lipid bilayers are well-described by our model, and provides $\\kappa_A$ in agreement with literature values. The liquid ordered phase has a yield like response that we model by hydrogen bond breaking.

  4. Direct probe of anisotropy in atom-molecule collisions via quantum scattering resonances

    CERN Document Server

    Klein, Ayelet; Skomorowski, Wojciech; Żuchowski, Piotr S; Pawlak, Mariusz; Janssen, Liesbeth M C; Moiseyev, Nimrod; van de Meerakker, Sebastiaan Y T; van der Avoird, Ad; Koch, Christiane P; Narevicius, Edvardas

    2016-01-01

    Anisotropy is a fundamental property of particle interactions. It occupies a central role in cold and ultra-cold molecular processes, where long range forces have been found to significantly depend on orientation in ultra-cold polar molecule collisions. Recent experiments have demonstrated the emergence of quantum phenomena such as scattering resonances in the cold collisions regime due to quantization of the intermolecular degrees of freedom. Although these states have been shown to be sensitive to interaction details, the effect of anisotropy on quantum resonances has eluded experimental observation so far. Here, we directly measure the anisotropy in atom-molecule interactions via quantum resonances by changing the quantum state of the internal molecular rotor. We observe that a quantum scattering resonance at a collision energy of $k_B$ x 270 mK appears in the Penning ionization of molecular hydrogen with metastable helium only if the molecule is rotationally excited. We use state of the art ab initio and ...

  5. Whispering-gallery acoustic sensing: Characterization of mesoscopic films and scanning probe microscopy applications

    Science.gov (United States)

    La Rosa, Andres H.; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S. K.

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  6. Whispering-gallery acoustic sensing: characterization of mesoscopic films and scanning probe microscopy applications.

    Science.gov (United States)

    La Rosa, Andres H; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S K

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  7. Surface characterization of InP trenches embedded in oxide using scanning probe microscopy

    Science.gov (United States)

    Mannarino, Manuel; Chintala, Ravi; Moussa, Alain; Merckling, Clement; Eyben, Pierre; Paredis, Kristof; Vandervorst, Wilfried

    2015-12-01

    Metrology for structural and electrical analyses at device level has been identified as one of the major challenges to be resolved for the sub-14 nm technology nodes. In these advanced nodes, new high mobility semiconductors, such as III-V compounds, are grown in narrow trenches on a Si substrate. Probing the nature of the defects, the defect density, and the role of processing steps on the surface of such structures are prime metrology requirements. In order to enable defect analysis on a (III-V) surface, a proper sample preparation for oxide removal is of primary importance. In this work, the effectiveness of different chemical cleanings and thermal annealing procedures is investigated on both blanket InP and oxide embedded InP trenches by means of scanning probe microscopy techniques. It is found that the most effective approach is a combination of an HCl-based chemical cleaning combined with a low-temperature thermal annealing leading to an oxide free surface with atomically flat areas. Scanning tunneling microscopy (STM) has been the preferred method for such investigations on blanket films due to its intrinsic sub-nm spatial resolution. However, its application on oxide embedded structures is non-trivial. To perform STM on the trenches of interest (generally <20 nm wide), we propose a combination of non-contact atomic force microscopy and STM using the same conductive atomic force microscopy tip Our results prove that with these procedures, it is possible to perform STM in narrow InP trenches showing stacking faults and surface reconstruction. Significant differences in terms of roughness and terrace formation are also observed between the blanket and the oxide embedded InP.

  8. Nanostructural evolution of Cr-rich precipitates in a Cu-Cr-Zr alloy during heat treatment studied by 3 dimensional atom probe

    DEFF Research Database (Denmark)

    Hatakeyama, Masahiko; Toyama, Takeshi; Nagai, Yasuyoshi;

    2008-01-01

    Nanostructural evolution of Cr (Cr-rich) precipitates in a Cu-0.78%Cr-0.13%Zr alloy has been studied after aging and overaging (reaging) by laser assisted local electrode 3 dimensional atom probe (Laser-LEAP). This material is a candidate for the first wall and divertor components of future fusion...

  9. Perfect/complete scattering experiments probing quantum mechanics on atomic and molecular collisions and coincidences

    CERN Document Server

    Kleinpoppen, Hans; Grum-Grzhimailo, Alexei N

    2013-01-01

    The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter.  The feasibility of such perfect' and-or `complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory.  It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment `complete'.  The language of the related theory is the language of quantum mechanical amplitudes and their relative phases.  This book captures the spi...

  10. Characterizing the spin state of an atomic ensemble using the magneto-optical resonance method

    CERN Document Server

    Julsgaard, B; Sherson, J; Sørensen, J L

    2004-01-01

    Quantum information protocols utilizing atomic ensembles require preparation of a coherent spin state (CSS) of the ensemble as an important starting point. We investigate the magneto-optical resonance method for characterizing a spin state of cesium atoms in a paraffin coated vapor cell. Atoms in a constant magnetic field are subject to an off-resonant laser beam and an RF magnetic field. The spectrum of the Zeeman sub-levels, in particular the weak quadratic Zeeman effect, enables us to measure the spin orientation, the number of atoms, and the transverse spin coherence time. Notably the use of 894nm pumping light on the D1-line, ensuring the state F=4, m_F=4 to be a dark state, helps us to achieve spin orientation of better than 98%. Hence we can establish a CSS with high accuracy which is critical for the analysis of the entangled states of atoms.

  11. Dynamic characterization of silicon nanowires using a terahertz optical asymmetric demultiplexer-based pump-probe scheme

    DEFF Research Database (Denmark)

    Ji, Hua; Cleary, C. S.; Dailey, J. M.;

    2012-01-01

    Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers....

  12. Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials

    Science.gov (United States)

    Callewaert, Vincent; Shastry, K.; Saniz, Rolando; Makkonen, Ilja; Barbiellini, Bernardo; Assaf, Badih A.; Heiman, Donald; Moodera, Jagadeesh S.; Partoens, Bart; Bansil, Arun; Weiss, A. H.

    2016-09-01

    Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control, and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states and that the associated annihilation spectrum provides a technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of Eb=2.7 ±0.2 eV is presented and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and show the feasibility to detect their spin texture through the use of spin-polarized positron beams.

  13. Four-probe electrical characterization of Pt-coated TMV-based nanostructures.

    Science.gov (United States)

    Górzny, M L; Walton, A S; Wnęk, M; Stockley, P G; Evans, S D

    2008-04-23

    The electrical transport and structural properties of tobacco mosaic virus (TMV)-based nanostructures have been studied. Electroless deposition was used to coat the TMV outer surface with a 13 nm thick homogeneous Pt layer. SEM, TEM and electrical characterization of the obtained nanostructures has been performed. Using four independently controlled scanning tunnelling microscope tips we were able to perform four-point probe resistance measurements on linear virus assemblies and demonstrate the continuous nature of the metallic coating. The measured resistivity values of the virial nanowires exceeded the bulk value by 10-100 times; notwithstanding this the coated structure allowed high current densities, of the order of 10(5)-10(8) A cm(-2). The four-probe technique proved to be useful for analysing the electrical properties of bio-inorganic nanowires. PMID:21825656

  14. Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

    Science.gov (United States)

    Zhang, Xiaofei; Ye, Xuan; Li, Xide

    2016-08-01

    In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

  15. Probing the interaction of individual amino acids with inorganic surfaces using atomic force spectroscopy.

    Science.gov (United States)

    Razvag, Yair; Gutkin, Vitaly; Reches, Meital

    2013-08-13

    This article describes single-molecule force spectroscopy measurements of the interaction between individual amino acid residues and inorganic surfaces in an aqueous solution. In each measurement, there is an amino acid residue, lysine, glutamate, phenylalanine, leucine, or glutamine, and each represents a class of amino acids (positively or negatively charged, aromatic, nonpolar, and polar). Force-distance curves measured the interaction of the individual amino acid bound to a silicon atomic force microscope (AFM) tip with a silcon substrate, cut from a single-crystal wafer, or mica. Using this method, we were able to measure low adhesion forces (below 300 pN) and could clearly determine the strength of interactions between the individual amino acid residues and the inorganic substrate. In addition, we observed how changes in the pH and ionic strength of the solution affected the adsorption of the residues to the substrates. Our results pinpoint the important role of hydrophobic interactions among the amino acids and the substrate, where hydrophobic phenylalanine exhibited the strongest adhesion to a silicon substrate. Additionally, electrostatic interactions also contributed to the adsorption of amino acid residues to inorganic substrates. A change in the pH or ionic strength values of the buffer altered the strength of interactions among the amino acids and the substrate. We concluded that the interplay between the hydrophobic forces and electrostatic interactions will determine the strength of adsorption among the amino acids and the surface. Overall, these results contribute to our understanding of the interaction at the organic-inorganic interface. These results may have implications for our perception of the specificity of peptide binding to inorganic surfaces. Consequently, it would possibly lead to a better design of composite materials and devices.

  16. Quantifying, characterizing, and controlling information flow in ultracold atomic gases

    Energy Technology Data Exchange (ETDEWEB)

    Haikka, P. [Turku Center for Quantum Physics, Department of Physics and Astronomy, University of Turku, FIN-20014 Turku (Finland); McEndoo, S.; Maniscalco, S. [Turku Center for Quantum Physics, Department of Physics and Astronomy, University of Turku, FIN-20014 Turku (Finland); SUPA, EPS/Physics, Heriot-Watt University, Edinburgh, EH144AS (United Kingdom); De Chiara, G. [Fisica Teorica: Informacio i Fenomens Quantics, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Palma, G. M. [NEST Istituto Nanoscienze-CNR and Dipartimento di Fisica, Universita degli Studi di Palermo, via Archirafi 36, I-90123 Palermo (Italy)

    2011-09-15

    We study quantum information flow in a model comprised of a trapped impurity qubit immersed in a Bose-Einstein-condensed reservoir. We demonstrate how information flux between the qubit and the condensate can be manipulated by engineering the ultracold reservoir within experimentally realistic limits. We show that this system undergoes a transition from Markovian to non-Markovian dynamics, which can be controlled by changing key parameters such as the condensate scattering length. In this way, one can realize a quantum simulator of both Markovian and non-Markovian open quantum systems, the latter ones being characterized by a reverse flow of information from the background gas (reservoir) to the impurity (system).

  17. Characterization of positional errors and their influence on micro four-point probe measurements on a 100 nm Ru film

    International Nuclear Information System (INIS)

    Thin-film sheet resistance measurements at high spatial resolution and on small pads are important and can be realized with micrometer-scale four-point probes. As a result of the small scale the measurements are affected by electrode position errors. We have characterized the electrode position errors in measurements on Ru thin film using an Au-coated 12-point probe. We show that the standard deviation of the static electrode position error is on the order of 5 nm, which significantly affects the results of single configuration measurements. Position-error-corrected dual-configuration measurements, however, are shown to eliminate the effect of position errors to a level limited either by electrical measurement noise or dynamic position errors. We show that the probe contact points remain almost static on the surface during the measurements (measured on an atomic scale) with a standard deviation of the dynamic position errors of 3 Å. We demonstrate how to experimentally distinguish between different sources of measurement errors, e.g. electrical measurement noise, probe geometry error as well as static and dynamic electrode position errors. (paper)

  18. Quantitative characterization of crosstalk effects for friction force microscopy with scan-by-probe SPMs.

    Science.gov (United States)

    Prunici, Pavel; Hess, Peter

    2008-06-01

    If the photodetector and cantilever of an atomic force microscope (AFM) are not properly adjusted, crosstalk effects will appear. These effects disturb measurements of the absolute vertical and horizontal cantilever deflections, which are involved in friction force microscopy (FFM). A straightforward procedure is proposed to study quantitatively crosstalk effects observed in scan-by-probe SPMs. The advantage of this simple, fast, and accurate procedure is that no hardware change or upgrade is needed. The results indicate that crosstalk effects depend not only on the alignment of the detector but also on the cantilever properties, position, and detection conditions. The measurements may provide information on the origin of the crosstalk effect. After determination of its magnitude, simple correction formulas can be applied to correct the crosstalk effects and then the single-load wedge method, using a commercially available grating, can be employed for accurate calibration of the lateral force. PMID:18035500

  19. Gold-decorated highly ordered self-organized grating-like nanostructures on Ge surface: Kelvin probe force microscopy and conductive atomic force microscopy studies.

    Science.gov (United States)

    Mollick, Safiul Alam; Kumar, Mohit; Singh, Ranveer; Satpati, Biswarup; Ghose, Debabrata; Som, Tapobrata

    2016-10-28

    Nanoarchitecture by atomic manipulation is considered to be one of the emerging trends in advanced functional materials. It has a gamut of applications to offer in nanoelectronics, chemical sensing, and nanobiological science. In particular, highly ordered one-dimensional semiconductor nanostructures fabricated by self-organization methods are in high demand for their high aspect ratios and large number of applications. An efficient way of fabricating semiconductor nanostructures is by molecular beam epitaxy, where atoms are added to a crystalline surface at an elevated temperature during growth, yielding the desired structures in a self-assembled manner. In this article, we offer a room temperature process, in which atoms are sputtered away by ion impacts. Using gold ion implantation, the present study reports on the formation of highly ordered self-organized long grating-like nanostructures, with grooves between them, on a germanium surface. The ridges of the patterns are shown to have flower-like protruding nanostructures, which are mostly decorated by gold atoms. By employing local probe microscopic techniques like Kelvin probe force microscopy and conductive atomic force microscopy, we observe a spatial variation in the work function and different nanoscale electrical conductivity on the ridges of the patterns and the grooves between them, which can be attributed to gold atom decorated ridges. Thus, the architecture  presented offers the advantage of using the patterned germanium substrates as periodic arrays of conducting ridges and poorly conducting grooves between them. PMID:27655211

  20. Gold-decorated highly ordered self-organized grating-like nanostructures on Ge surface: Kelvin probe force microscopy and conductive atomic force microscopy studies

    Science.gov (United States)

    Alam Mollick, Safiul; Kumar, Mohit; Singh, Ranveer; Satpati, Biswarup; Ghose, Debabrata; Som, Tapobrata

    2016-10-01

    Nanoarchitecture by atomic manipulation is considered to be one of the emerging trends in advanced functional materials. It has a gamut of applications to offer in nanoelectronics, chemical sensing, and nanobiological science. In particular, highly ordered one-dimensional semiconductor nanostructures fabricated by self-organization methods are in high demand for their high aspect ratios and large number of applications. An efficient way of fabricating semiconductor nanostructures is by molecular beam epitaxy, where atoms are added to a crystalline surface at an elevated temperature during growth, yielding the desired structures in a self-assembled manner. In this article, we offer a room temperature process, in which atoms are sputtered away by ion impacts. Using gold ion implantation, the present study reports on the formation of highly ordered self-organized long grating-like nanostructures, with grooves between them, on a germanium surface. The ridges of the patterns are shown to have flower-like protruding nanostructures, which are mostly decorated by gold atoms. By employing local probe microscopic techniques like Kelvin probe force microscopy and conductive atomic force microscopy, we observe a spatial variation in the work function and different nanoscale electrical conductivity on the ridges of the patterns and the grooves between them, which can be attributed to gold atom decorated ridges. Thus, the architecture presented offers the advantage of using the patterned germanium substrates as periodic arrays of conducting ridges and poorly conducting grooves between them.

  1. Optimisation of sample preparation and analysis conditions for atom probe tomography characterisation of low concentration surface species

    Science.gov (United States)

    Douglas, J. O.; Bagot, P. A. J.; Johnson, B. C.; Jamieson, D. N.; Moody, M. P.

    2016-08-01

    The practicalities for atom probe tomography (APT) analysis of near-surface chemistry, particularly the distribution of low concentration elements, are presented in detail. Specifically, the challenges of surface analysis using APT are described through the characterisation of near-surface implantation profiles of low concentration phosphorus into single crystal silicon. This material system was chosen to illustrate this surface specific approach as low concentration phosphorus has significant mass spectra overlaps with silicon species and the near surface location requires particular attention to focused ion beam specimen preparation and deposition of various capping layers. Required changes to standard sample preparation procedure are described and the effects of changes in APT analysis parameters are discussed with regards to this specific material system. Implantation profiles of 14 kV phosphorus ions with a predicted peak concentration of 0.2 at .% were successfully analysed using APT using pulsed laser assisted evaporation. It is demonstrated that the most important factor in obtaining the most accurate implantation profile was to ensure all phosphorus mass peaks were as free of background noise as possible, with thermal tails from the Si2+ ions obscuring the P2+ ions being the major overlap in the mass spectrum. The false positive contribution to the phosphorus profiles from hydride species appears minimal at the capping layer/substrate interface. The initial capping layer selection of nickel was successful in allowing the analysis of the majority of the phosphorus profile but nickel and phosphorus mass spectra overlaps prevent optimum quantification of phosphorus at the surface.

  2. Temperature and force dependence of electron transport via the copper protein azurin: conductive probe atomic force microscopy measurements

    CERN Document Server

    Li, Wenjie; Amdursky, Nadav; Cohen, Sidney R; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2012-01-01

    We report conducting probe atomic force microscopy (CP-AFM) measurements of electron transport (ETp), as a function of temperature and force, through monolayers of holo-azurin (holo-Az) and Cu-depleted Az (apo-Az) that retain only their tightly bound water, immobilized on gold surfaces. The changes in CP-AFM current-voltage (I-V) curves for holo-Az and apo-Az, measured between 250 - 370K, are strikingly different. While ETp across holo-Az at low force (6 nN) is temperature-independent over the whole examined range, ETp across apo-Az is thermally activated, with calculated activation energy of 600\\pm100 meV. These results confirm our results of macroscopic contact area ETp measurements via holo- and apo-Az, as a function of temperature, where the crucial role of the Cu redox centre has been observed. While increasing the applied tip force from 6 to 12 nN did not significantly change the temperature dependence of ETp via apo-Az, ETp via holo-Az changed qualitatively, namely from temperature-independent at 6 nN ...

  3. Intergranular segregation in the pressure vessel steel of a commercial nuclear reactor studied by atom probe tomography

    International Nuclear Information System (INIS)

    Solute/impurity segregation and precipitation at grain boundaries (GBs) in a nuclear reactor pressure vessel (RPV) steel were investigated using laser-assisted atom probe tomography (APT): RPV surveillance test specimens irradiated in a commercial nuclear reactor to neutron doses of 0.83 x 1019 n·cm-2 (low-dose) and 5.1 x 1019 n·cm-2 (high-dose), corresponding to in-service exposure of ∼5 and ∼30 years, respectively. The segregation of C, P and Mo was found on GBs after the low-dose irradiation. The segregation of Si and Mn as well as C, P and Mo was observed after the high-dose irradiation. The monolayer coverage of P is estimated to be less than a suggested level for intergranular embrittlement. The segregation of C, P and Mo was also observed along parallel array of dislocation lines in small-angle grain boundaries. However, no segregation of Si and Mn was detected there. Copper-nano precipitates (CNPs) were observed on the GBs, along the dislocation lines and in the matrix. The sizes and the solute-impurity enrichment in these CNPs are compared. (author)

  4. Microstructural evolution of Fesbnd 22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

    Science.gov (United States)

    Korchuganova, Olesya A.; Thuvander, Mattias; Aleev, Andrey A.; Rogozhkin, Sergey V.; Boll, Torben; Kulevoy, Timur V.

    2016-08-01

    Nanostructure evolution during ion irradiation of two thermally aged binary Fee22Cr alloys has been investigated using atom probe tomography. Specimens aged at 500 °C for 50 and 200 h were irradiated by 5.6 MeV Fe ions at room temperature up to fluences of 0.3 × 1015 ions/cm2 and 1 × 1015 ions/cm2. The effect of irradiation on the material nanostructure was examined at a depth of 1 μm from the irradiated surface. The analysis of Cr radial concentration functions reveals that dense α‧-phase precipitates in the 200 h aged alloy become diffuse and thereby larger when subjected to irradiation. On the other hand, less Cr-enriched precipitates in the alloy aged for 50 h are less affected. The CreCr pair correlation function analysis shows that matrix inhomogeneity decreases under irradiation. Irradiation leads to a decrease in the number density of diffuse clusters, whereas in the case of well-developed precipitates it remains unchanged.

  5. Atom probe tomography of a Ti-Si-Al-C-N coating grown on a cemented carbide substrate.

    Science.gov (United States)

    Thuvander, M; Östberg, G; Ahlgren, M; Falk, L K L

    2015-12-01

    The elemental distribution within a Ti-Si-Al-C-N coating grown by physical vapour deposition on a Cr-doped WC-Co cemented carbide substrate has been investigated by atom probe tomography. Special attention was paid to the coating/substrate interface region. The results indicated a diffusion of substrate binder phase elements into the Ti-N adhesion layer. The composition of this layer, and the Ti-Al-N interlayer present between the adhesion layer and the main Ti-Si-Al-C-N layer, appeared to be sub-stoichiometric. The analysis of the interlayer showed the presence of internal surfaces, possibly grain boundaries, depleted in Al. The composition of the main Ti-Al-Si-C-N layer varied periodically in the growth direction; layers enriched in Ti appeared with a periodicity of around 30 nm. Laser pulsing resulted in a good mass resolution that made it possible to distinguish between N(+) and Si(2+) at 14 Da.

  6. Characterization of the ER-Targeted Low Affinity Ca(2+) Probe D4ER.

    Science.gov (United States)

    Greotti, Elisa; Wong, Andrea; Pozzan, Tullio; Pendin, Diana; Pizzo, Paola

    2016-01-01

    Calcium ion (Ca(2+)) is a ubiquitous intracellular messenger and changes in its concentration impact on nearly every aspect of cell life. Endoplasmic reticulum (ER) represents the major intracellular Ca(2+) store and the free Ca(2+) concentration ([Ca(2+)]) within its lumen ([Ca(2+)]ER) can reach levels higher than 1 mM. Several genetically-encoded ER-targeted Ca(2+) sensors have been developed over the last years. However, most of them are non-ratiometric and, thus, their signal is difficult to calibrate in live cells and is affected by shifts in the focal plane and artifactual movements of the sample. On the other hand, existing ratiometric Ca(2+) probes are plagued by different drawbacks, such as a double dissociation constant (Kd) for Ca(2+), low dynamic range, and an affinity for the cation that is too high for the levels of [Ca(2+)] in the ER lumen. Here, we report the characterization of a recently generated ER-targeted, Förster resonance energy transfer (FRET)-based, Cameleon probe, named D4ER, characterized by suitable Ca(2+) affinity and dynamic range for monitoring [Ca(2+)] variations within the ER. As an example, resting [Ca(2+)]ER have been evaluated in a known paradigm of altered ER Ca(2+) homeostasis, i.e., in cells expressing a mutated form of the familial Alzheimer's Disease-linked protein Presenilin 2 (PS2). The lower Ca(2+) affinity of the D4ER probe, compared to that of the previously generated D1ER, allowed the detection of a conspicuous, more clear-cut, reduction in ER Ca(2+) content in cells expressing mutated PS2, compared to controls. PMID:27598166

  7. Characterization of the ER-Targeted Low Affinity Ca2+ Probe D4ER

    Directory of Open Access Journals (Sweden)

    Elisa Greotti

    2016-09-01

    Full Text Available Calcium ion (Ca2+ is a ubiquitous intracellular messenger and changes in its concentration impact on nearly every aspect of cell life. Endoplasmic reticulum (ER represents the major intracellular Ca2+ store and the free Ca2+ concentration ([Ca2+] within its lumen ([Ca2+]ER can reach levels higher than 1 mM. Several genetically-encoded ER-targeted Ca2+ sensors have been developed over the last years. However, most of them are non-ratiometric and, thus, their signal is difficult to calibrate in live cells and is affected by shifts in the focal plane and artifactual movements of the sample. On the other hand, existing ratiometric Ca2+ probes are plagued by different drawbacks, such as a double dissociation constant (Kd for Ca2+, low dynamic range, and an affinity for the cation that is too high for the levels of [Ca2+] in the ER lumen. Here, we report the characterization of a recently generated ER-targeted, Förster resonance energy transfer (FRET-based, Cameleon probe, named D4ER, characterized by suitable Ca2+ affinity and dynamic range for monitoring [Ca2+] variations within the ER. As an example, resting [Ca2+]ER have been evaluated in a known paradigm of altered ER Ca2+ homeostasis, i.e., in cells expressing a mutated form of the familial Alzheimer’s Disease-linked protein Presenilin 2 (PS2. The lower Ca2+ affinity of the D4ER probe, compared to that of the previously generated D1ER, allowed the detection of a conspicuous, more clear-cut, reduction in ER Ca2+ content in cells expressing mutated PS2, compared to controls.

  8. A novel approach for site-specific atom probe specimen preparation by focused ion beam and transmission electron backscatter diffraction

    International Nuclear Information System (INIS)

    Atom probe tomography (APT) is a suitable technique for chemical analyses with almost atomic resolution. However, the time-consuming site-specific specimen preparation can be improved. Recently, transmission electron backscatter diffraction (t-EBSD) has been established for high resolution crystallographic analyses of thin foils. In this paper we present the first successful application of a combined focused ion beam (FIB)/t-EBSD preparation of site-specific APT specimens using the example of grain boundary segregation in technically pure molybdenum. It will be shown that the preparation of a grain boundary can be substantially accelerated by t-EBSD analyses in-between the annular milling FIB procedure in the same microscope. With this combined method, a grain boundary can easily be recognized and positioned in the first 220 nm of an APT sample much faster than e.g. with complementary investigations in a transmission electron microscope. Even more, the high resolution technique of t-EBSD gives the opportunity to get crystallographic information of the mapped area and, therefore, an analysis of the grain boundary character to support the interpretation of the APT data files. To optimize this newly developed technique for the application on needle-shaped APT specimens, a parameter study on enhanced background correction, acceleration voltage, and tilt angle was carried out. An acceleration voltage of 30 kV at specimen surface tilt angles between −45° and −35° from horizontal plane leads to the best results. Even for molybdenum the observation of crystal orientation data up to about 200 nm specimen thickness is possible. - Highlights: • We developed a new site-specific APT specimen preparation method by FIB and t-EBSD. • A grain boundary was positioned in the first 220 nm of the APT tip by the FIB/t-EBSD method. • Crystallographic information of the mapped area can be quickly obtained. • An acceleration voltage of 30 kV at specimen surface tilt angles

  9. An integrated and multi-purpose microscope for the characterization of atomically thin optoelectronic devices

    CERN Document Server

    De Sanctis, Adolfo; Townsend, Nicola J; Craciun, Monica F; Russo, Saverio

    2016-01-01

    Optoelectronic devices based on graphene and other two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs) are the focus of wide research interest. They can be the key to improving bandwidths in telecommunications, capacity in data storage, new features in consumer electronics, safety devices and medical equipment. The characterization these emerging atomically thin materials and devices strongly relies on a set of measurements involving both optical and electronic instrumentation ranging from scanning photocurrent mapping to Raman and photoluminescence (PL) spectroscopy. Current state-of-the-art commercial instruments offer the ability to characterize individual properties of these materials with no option for the in situ characterization of a wide enough range of complementary optical and electrical properties. Presently, the requirement to switch atomically-thin materials from one system to another often radically affects the properties of these uniquely sensitive materials through ...

  10. Electrical Capacitance Probe Characterization in Vertical Annular Two-Phase Flow

    Directory of Open Access Journals (Sweden)

    Grazia Monni

    2013-01-01

    Full Text Available The paper presents the experimental analysis and the characterization of an electrical capacitance probe (ECP that has been developed at the SIET Italian Company, for the measurement of two-phase flow parameters during the experimental simulation of nuclear accidents, as LOCA. The ECP is used to investigate a vertical air/water flow, characterized by void fraction higher than 95%, with mass flow rates ranging from 0.094 to 0.15 kg/s for air and from 0.002 to 0.021 kg/s for water, corresponding to an annular flow pattern. From the ECP signals, the electrode shape functions (i.e., the signals as a function of electrode distances in single- and two-phase flows are obtained. The dependence of the signal on the void fraction is derived and the liquid film thickness and the phase’s velocity are evaluated by means of rather simple models. The experimental analysis allows one to characterize the ECP, showing the advantages and the drawbacks of this technique for the two-phase flow characterization at high void fraction.

  11. Characterization of Residual Stresses in Ferrous Components by Magnetic Anisotropy Measurements Using a Hall Effect Sensor Array Probe

    Science.gov (United States)

    Lo, C. C. H.

    2011-06-01

    A new surface sensor probe comprising an angular array of Hall effect sensors has been developed for characterization of residual stresses in ferrous materials by means of stress-induced magnetic anisotropy measurements. The sensor probe applies a radially spreading ac magnetic field to a test sample, and detects stray fields in different directions simultaneously to determine the principal stress axes. In situ measurements were conducted on a annealed steel plate under four-point bending stresses to evaluate the probe performance. The ratio of stray field signals measured along and perpendicular to the stress axis varies linearly with the surface stress, indicating the possibility of characterizing residual stresses in ferrous components using the sensor array probe.

  12. An Atom Probe Tomographic Investigation of High-Strength, High-Toughness Precipitation Strengthened Steels for Naval Applications

    Science.gov (United States)

    Hunter, Allen H.

    Novel high-strength high-toughness alloys strengthened by precipitation are investigated for use in naval applications. The mechanical properties of an experimental steel alloy, NUCu-140, are evaluated and are not suitable for the naval requirements due to poor impact toughness at -40°C. An investigation is conducted to determine optimum processing conditions to restore toughness. A detailed aging study is conducted at 450, 500, and 550°C to determine the evolution of the microstructure and mechanical properties. A combination of transmission electron microscopy (TEM), synchrotron X-ray Diffraction (XRD), and Local electrode atom probe (LEAP) tomography are used to measure the evolution of the Cu precipitates, austenite, NbC, and cementite phases during aging. The evolution of the Cu precipitates significantly affects the yield strength of the steel, but low temperature toughness is controlled by the cementite precipitates. Extended aging is effective at improving the impact toughness but the yield strength is also decreased due to coarsening of the Cu precipitates. To provide a foundation for successful welding of NUCu-140 steel, an investigation of the effects of gas metal arc welding (GMAW) are performed. The microstructures in the base metal (BM), heat affected zone (HAZ), and fusion zone (FZ) of a GMAW sample are analyzed to determine the effects of the welding thermal cycle. Weld simulation samples with known thermal histories are prepared and analyzed by XRD and LEAP tomography. A significant loss in microhardness is observed as a result of dissolution of the Cu precipitates after the weld thermal cycle. The cooling time is too rapid to allow significant precipitation of Cu. In addition to the NUCu-140 alloy, a production HSLA-115 steel alloy is investigated using TEM, XRD, and LEAP tomography. The strength of the HSLA-115 is found to be derived primarily from Cu precipitates. The volume fractions of cementite, austenite, and NbC are measured by XRD

  13. Laser-induced reversion of $\\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    OpenAIRE

    Khushaim, Muna; Gemma, Ryota; Al-Kassab, Talaat

    2015-01-01

    The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser ene...

  14. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    Science.gov (United States)

    Vecchiola, Aymeric; Chrétien, Pascal; Delprat, Sophie; Bouzehouane, Karim; Schneegans, Olivier; Seneor, Pierre; Mattana, Richard; Tatay, Sergio; Geffroy, Bernard; Bonnassieux, Yvan; Mencaraglia, Denis; Houzé, Frédéric

    2016-06-01

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  15. Effect of the interaction conditions of the probe of an atomic-force microscope with the n-GaAs surface on the triboelectrization phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Baklanov, A. V., E-mail: baklanov@mail.ioffe.ru [St. Petersburg State Polytechnical University, Institute of Physics, Nanotechnology, and Telecommunications (Russian Federation); Gutkin, A. A.; Kalyuzhnyy, N. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Brunkov, P. N. [St. Petersburg State Polytechnical University, Institute of Physics, Nanotechnology, and Telecommunications (Russian Federation)

    2015-08-15

    Triboelectrization as a result of the scanning of an atomic-force-microscope probe over an n-GaAs surface in the contact mode is investigated. The dependences of the local potential variation on the scanning rate and the pressing force of the probe are obtained. The results are explained by point-defect formation in the surface layers of samples under the effect of deformation of these layers during probe scanning. The charge localized at these defects in the case of equilibrium changes the potential of surface, which is subject to triboelectrization. It is shown that, for qualitative explanation of the observed dependences, it is necessary to take into account both the generation and annihilation of defects in the region experiencing deformation.

  16. Probing Interaction Between Platinum Group Metal (PGM) and Non-PGM Support Through Surface Characterization and Device Performance

    Science.gov (United States)

    Saha, Shibely

    High cost and limited abundance of Platinum (Pt) have hindered effective commercialization of Proton Exchange Membrane Fuel Cell and Electrolyzer. Efforts have been undertaken to reduce precious group metal (PGM) requirement for these devices without compromising the activity of the catalyst by using transition metal carbides (TMC) as non-PGM support thanks to their similar electronic and geometric structures as Pt. In this work Mo2C was selected as non-PGM support and Pt was used as the PGM of interest. We hypothesize that the hollow nanotube morphology of Mo2C support combined with Pt nano particles deposited on it via atomic layer deposition (ALD) technique would allow increased interaction between them which may increase the activity of Pt and Mo2C as well as maximize the Pt active surface area. Specifically, a rotary ALD equipment was used to grow Pt particles from atomic level to 2--3 nanometers by simply adjusting number of ALD cycles in order to probe the interaction between the deposited Pt nanoparticles and Mo2C nanotube support. Interaction between the Pt and Mo2 C was analyzed via surface characterization and electrochemical characterization. Interaction between Pt and Mo2C arises due to the lattice mismatch between Pt and Mo2C as well as electron migration between them. Lattice spacing analysis using high resolution transmission electron microscopy (HRTEM) images, combined with Pt binding energy shift in XPS results, clearly showed strong bonding between Pt nanoparticles and the Mo2C nanotube support in all the resultant Pt/Mo2C samples. We postulate that this strong interaction is responsible for the significantly enhanced durability observed in our constant potential electrolysis (CPE) and accelerated degradation testing (ADT). Of the three samples from different ALD cycles (15, 50 and 100), Mo2C nanotubes modified by 50 (1.07 wt% Pt loading) and 100 cycles (4.4 wt% Pt) of Pt deposition, showed higher HER and HOR activity per Pt mass than commercial

  17. New insight into direct electrical characterization of graphene utilizing cleavage-based micro four probe

    Science.gov (United States)

    Wang, Renxin; Zhang, Hongze; Wang, Wen; Zhang, Yushi; Liu, Yuan; Xu, Wei; Li, Zhihong

    2016-07-01

    To characterize the electrical properties of arbitrarily shaped small graphene flakes in a direct way, a kind of cleavage-based micro four probe (C-M4P) is developed and a finite element analysis (FEA)-aided approximation method is subsequently proposed. The cleavage process is put forward in the manufacturing of C-M4Ps, which fulfills the releasing of the C-M4P in an ingenious manner. Specifically, we investigate the cleavage process based on simulation and the scanning electron micrograph (SEM). Furthermore, the FEA-aided approximation method brings new insight into the conductivity characterization of arbitrarily shaped small graphene flakes when the geographic correction factor is non-negligible but complicated to figure out. The electrical properties of monolayer graphene flakes applied with back gate voltage are detected by the C-M4P and analyzed through the FEA-aided approximation method, which are proved to be competent for small graphene flake characterization.

  18. Structure–performance characterization for carbon molecular sieve membranes using molecular scale gas probes

    KAUST Repository

    Rungta, Meha

    2015-04-01

    © 2015 Elsevier Ltd. All rights reserved. Understanding the relationship between carbon molecular sieve (CMS) pore structure and corresponding gas separation performance enables optimization for a given gas separation application. The final pyrolysis temperature and starting polymer precursor are the two critical parameters in controlling CMS performance. This study considers structure and performance changes of CMS derived from a commercially available polymer precursor at different pyrolysis temperatures. As reviewed in this paper, most traditional characterization methods based on microscopy, X-ray diffraction, spectroscopy, sorption-based pore size distribution measurements etc. provide limited information for relating separation performance to the CMS morphology and structural changes. A useful alternative approach based on different sized gases as molecular scale probes of the CMS pore structure was successfully used here in conjunction with separation data to provide critical insights into the structure-performance relationships of the engineered CMS.

  19. Spectroscopic characterization of fluorine atoms in atmospheric pressure He/SF6 plasmas

    Institute of Scientific and Technical Information of China (English)

    Huiliang Jin; Bo Wang; Feihu Zhang

    2011-01-01

    We investigate reactive fluorine atom spectroscopic characterization in atmospheric pressure of He/SF6 plasma using atomic emission spectrometry. As input radio frequency (RF) power levels are raised from 140 to 220 W, the emission spectra of 685.60 (3p4D→3s4P transition) and 739.87 nm (3p4P→3s4P transition) increase significantly. Moreover, an optimal value of SF6 volume concentration in the production of fluorine radicals, which is 0.8% is achieved. Addition of certain amounts of O2 into He/SF6 plasma results in the promotion of SF6 dissociation. Emission intensities of fluorine atoms show the maximum at the O2/SF6 ratio of 0.4.%@@ We investigate reactive fluorine atom spectroscopic characterization in atmospheric pressure of He/SF6plasma using atomic emission spectrometry.As input radio frequency (RF) power levels are raised from 140to 220 W, the emission spectra of 685.60 (3p4D→3s4P transition) and 739.87 nm (3p4P→3s4P transition)increase significantly.Moreover, an optimal value of SF6 volume concentration in the production of fluorine radicals, which is 0.8% is achieved.Addition of certain amounts of O2 into He/SF6 plasma results in the promotion of SF6 dissociation.Emission intensities of fluorine atoms show the maximum at the O2/SF6ratio of 0.4.

  20. Ordering and site occupancy of D03 ordered Fe3Al-5 at%Cr evaluated by means of atom probe tomography

    KAUST Repository

    Rademacher, Thomas W.

    2011-05-01

    Addition of ternary elements to the D03 ordered Fe3Al intermetallic phase is a general approach to optimise its mechanical properties. To understand the physical influences of such additions the determination of the probability of site occupancies of these additions on the lattice site and ordering parameters is of high interest. Some common experimental techniques such as X-ray diffraction or Atom Location by Channelling Enhanced Microanalysis (ALCHEMI) are usually applied to explore this interplay. Unfortunately, certain published results are partly inconsistent, imprecise or even contradictory. In this study, these aspects are evaluated systematically by atom probe tomography (APT) and a special data analysis method. Additionally, to account for possible field evaporation effects that can falsify the estimation of site occupancy and induce misinterpretations, APT evaporation sequences were also simulated. As a result, chromium occupies most frequently the next nearest neighbour sites of Al atoms and local ordering parameters could be achieved. © 2010 Elsevier B.V.

  1. Characterization of positional errors and their influence on micro four-point probe measurements on a 100 nm Ru film

    DEFF Research Database (Denmark)

    Kjær, Daniel; Hansen, Ole; Østerberg, Frederik Westergaard;

    2015-01-01

    errors in measurements on Ru thin film using an Au-coated 12-point probe. We show that the standard deviation of the static electrode position error is on the order of 5 nm, which significantly affects the results of single configuration measurements. Position-error-corrected dual......-configuration measurements, however, are shown to eliminate the effect of position errors to a level limited either by electrical measurement noise or dynamic position errors. We show that the probe contact points remain almost static on the surface during the measurements (measured on an atomic scale) with a standard...... deviation of the dynamic position errors of 3 Å. We demonstrate how to experimentally distinguish between different sources of measurement errors, e.g. electrical measurement noise, probe geometry error as well as static and dynamic electrode position errors....

  2. Characterization of the geometry and topology of DNA pictured as a discrete collection of atoms

    OpenAIRE

    Clauvelin, Nicolas; Olson, Wilma K.; Tobias, Irwin

    2012-01-01

    The structural and physical properties of DNA are closely related to its geometry and topology. The classical mathematical treatment of DNA geometry and topology in terms of ideal smooth space curves was not designed to characterize the spatial arrangements of atoms found in high-resolution and simulated double-helical structures. We present here new and rigorous numerical methods for the rapid and accurate assessment of the geometry and topology of double-helical DNA structures in terms of t...

  3. Study of modification methods of probes for critical-dimension atomic-force microscopy by the deposition of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ageev, O. A., E-mail: ageev@sfedu.ru [Southern Federal University, Institute for Nanotechnologies, Electronics, and Electronic Equipment Engineering (Russian Federation); Bykov, Al. V. [NT-MDT (Russian Federation); Kolomiitsev, A. S.; Konoplev, B. G.; Rubashkina, M. V.; Smirnov, V. A.; Tsukanova, O. G. [Southern Federal University, Institute for Nanotechnologies, Electronics, and Electronic Equipment Engineering (Russian Federation)

    2015-12-15

    The results of an experimental study of the modification of probes for critical-dimension atomicforce microscopy (CD-AFM) by the deposition of carbon nanotubes (CNTs) to improve the accuracy with which the surface roughness of vertical walls is determined in submicrometer structures are presented. Methods of the deposition of an individual CNT onto the tip of an AFM probe via mechanical and electrostatic interaction between the probe and an array of vertically aligned carbon nanotubes (VACNTs) are studied. It is shown that, when the distance between the AFM tip and a VACNT array is 1 nm and the applied voltage is within the range 20–30 V, an individual carbon nanotube is deposited onto the tip. On the basis of the results obtained in the study, a probe with a carbon nanotube on its tip (CNT probe) with a radius of 7 nm and an aspect ratio of 1:15 is formed. Analysis of the CNT probe demonstrates that its use improves the resolution and accuracy of AFM measurements, compared with the commercial probe, and also makes it possible to determine the roughness of the vertical walls of high-aspect structures by CD-AFM. The results obtained can be used to develop technological processes for the fabrication and reconditioning of special AFM probes, including those for CD-AFM, and procedures for the interoperational express monitoring of technological process parameters in the manufacturing of elements for micro- and nanoelectronics and micro- and nanosystem engineering.

  4. Design, fabrication and characterization of tunable external cavity diode laser and atom trapping chips for atomic physics

    Science.gov (United States)

    Chuang, Ho-Chiao

    External cavity diode laser systems (ECDLs) have been well documented for their suitability in the fields of laser cooling and atom trapping, and are now widely used in optical and atomic physics. A particularly simple implementation of this idea uses feedback from a diffraction grating mounted in the Littrow configuration and the typical size of this laser is quite large (120mmx90mmx90mm). For atom optics, the current atom trapping chips are not in a feedthrough configuration, which makes the chips to glass cell assembly process complicated and the wires and solder areas vulnerable, resulting in an unreliable vacuum seal. Recent experimental realizations of atom optical devices such as atomic waveguides, beam splitters, and on-chip Bose-Einstein condensate (BEC) sources have opened a new field for the development of more complex devices such as, e.g., BEC-based atom transistor. This work focuses on micro/nano fabrication techniques to build three different devices for the miniature BEC system. The research work focuses on the development of new ECDLs, a novel fabrication process of feedthrough atom trapping chips for atomic optics and a fabrication process for atom transistor chips. In the ECDLs part, we describe a new method for constructing a smaller external-cavity diode laser by use of a micromachined silicon flexure and a VHG (Volume Holographic Grating). It is much smaller, inexpensive and easy to build because it is based on simple modifications of a few commercial optical and mechanical components but with a specific silicon flexure design enabled by micro-fabrication technology for the laser frequency tuning. In the feedthrough chips part, we present a novel fabrication process for feedthrough atom trapping chips in atomic condensate optics cells using the copper electroplating to seal the vias. The advantages of using feedthrough atom trapping chips are the simple microfabrication process and reduction of the overall chip area bonded on the glass atom

  5. Atom probe tomography evidence for uniform incorporation of Bi across the growth front in GaAs1-xBix/GaAs superlattice

    Science.gov (United States)

    Chen, Weixin; Ronsheim, Paul A.; Wood, Adam W.; Forghani, Kamran; Guan, Yingxin; Kuech, Thomas F.; Babcock, Susan E.

    2016-07-01

    The three-dimensional distribution of Bi atoms in a GaAs1-xBix/GaAs superlattice grown by metalorganic vapor phase epitaxy (MOVPE) was studied using atom probe tomography (APT). The Bi distribution in the growth direction deduced from APT agreed quantitatively with the complex Bi concentration profile that was discovered using high-angle annular dark-field scanning transmission electron microscopy in a previous study. More importantly, APT revealed the Bi atom distribution in the growth planes at near atomic resolution. Bi nearest neighbor distribution and concentration frequency distribution analysis of the APT data indicated a statistically random distribution of Bi atoms in 1-2 nm thick layers oriented perpendicular to the growth direction. These results provide evidence that Bi is incorporated homogeneously across the growth front even when the concentration profile in the growth direction is complex. They also suggest that MOVPE growth conditions can promote uniform Bi distribution within GaAs1-xBix layers, opening a path for application of these materials in the optoelectronic devices for which they show much promise.

  6. Precision X-ray spectroscopy of kaonic atoms as a probe of low-energy kaon-nucleus interaction

    CERN Document Server

    Shi, H; Beer, G; Bellotti, G; Berucci, C; Bragadireanu, A M; Bosnar, D; Cargnelli, M; Curceanu, C; Butt, A D; d'Uffizi, A; Fiorini, C; Ghio, F; Guaraldo, C; Hayano, R S; Iliescu, M; Ishiwatari, T; Iwasaki, M; Sandri, P Levi; Marton, J; Okada, S; Pietreanu, D; Piscicchia, K; Vidal, A Romero; Sbardella, E; Scordo, A; Sirghi, D L; Sirghi, F; Tatsuno, H; Doce, O Vazquez; Widmann, E; Zmeskal, J

    2016-01-01

    In the exotic atoms where one atomic $1s$ electron is replaced by a $K^{-}$, the strong interaction between the $K^{-}$ and the nucleus introduces an energy shift and broadening of the low-lying kaonic atomic levels which are determined by only the electromagnetic interaction. By performing X-ray spectroscopy for Z=1,2 kaonic atoms, the SIDDHARTA experiment determined with high precision the shift and width for the $1s$ state of $K^{-}p$ and the $2p$ state of kaonic helium-3 and kaonic helium-4. These results provided unique information of the kaon-nucleus interaction in the low energy limit.

  7. Light-induced atom desorption from glass surfaces characterized by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Kumagai, Ryo; Hatakeyama, Atsushi

    2016-07-01

    We analyzed the surfaces of vitreous silica (quartz) and borosilicate glass (Pyrex) substrates exposed to rubidium (Rb) vapor by X-ray photoelectron spectroscopy (XPS) to understand the surface conditions of alkali metal vapor cells. XPS spectra indicated that Rb atoms adopted different bonding states in quartz and Pyrex. Furthermore, Rb atoms in quartz remained in the near-surface region, while they diffused into the bulk in Pyrex. For these characterized surfaces, we measured light-induced atom desorption (LIAD) of Rb atoms. Clear differences in time evolution, photon energy dependence, and substrate temperature dependence were found; the decay of LIAD by continuous ultraviolet irradiation for quartz was faster than that for Pyrex, a monotonic increase in LIAD with increasing photon energy from 1.8 to 4.3 eV was more prominent for quartz, and LIAD from quartz was more efficient at higher temperatures in the range from 300 to 580 K, while that from Pyrex was almost independent of temperature.

  8. Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation

    International Nuclear Information System (INIS)

    Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)

  9. New niobium and rhenium halides synthesis routes by atomic vaporization. X-ray absorption spectroscopy characterization

    International Nuclear Information System (INIS)

    New synthetic route as the so called 'chimie douce' or MVS (Metal Vapor Synthesis) has been an increasing field lately to synthesize new kind of solid state structures. Our interest is the assembly of small molecular building blocks of early transition metal halides. We illustrate the use of vaporized rare earth metals to condense NbCls units. We probed the local order around the Nb atom with X-Ray Absorption Spectroscopy, far Infra-Red and XPS in order to better understand the mechanisms involved. A first EXAFS, IR and XPS study on solid state products has shown the evolution of the NbCl5 dimer towards a chain like structure. However, the condensation patterns depends on the rare earth atoms vaporized. These results have been confirmed by X-ray Absorption ab initio calculations. Because our compounds are extremely air sensitive we have developed in situ MVS reactor to take 'snapshots' of the structural intermediates by EXAFS. This study showed the condensation of the initial NbCl5 building blocks by reduction of the Nb oxidation state by rare earth vaporization. This method is a new way of looking at condensation mechanisms via structural evolution observed by EXAFS. (author)

  10. Heat dissipation in atomic-scale junctions

    OpenAIRE

    Lee, Woochul; Kim, Kyeongtae; Jeong, Wonho; Zotti, Linda Angela; Pauly, Fabian; Cuevas, Juan Carlos; Reddy, Pramod

    2013-01-01

    Atomic and single-molecule junctions represent the ultimate limit to the miniaturization of electrical circuits. They are also ideal platforms for testing quantum transport theories that are required to describe charge and energy transfer in novel functional nanometre-scale devices. Recent work has successfully probed electric and thermoelectric phenomena in atomic-scale junctions. However, heat dissipation and transport in atomic-scale devices remain poorly characterized owing to experimenta...

  11. On the atomic force microscopy characterization of void evolution in severely plastic deformed pure iron

    Science.gov (United States)

    Forouzanmehr, N.; Nili-Ahmadabadi, N.

    2014-08-01

    Different severe plastic deformation comprise equal channel angular pressing (ECAP), shaped cold rolling and drawing, or combined were applied on pure iron to obtain nano structured grains. The results show the formation of high concentration of excess free volume up to about 4% in the cold rolled and drawn specimens. Emphasis has been placed on atomic force microscopy (AFM) observations as additional characterization tools that complement the information provided by other techniques. Since the surface of the materials can be observed with atomic-scale resolution, the AFM is a powerful technique to study porous materials. The microscopy observations detect voids in the nanocrystalline Fe sample- processed by shaped rolling followed by drawing with applied true strain of 7- from nano to sub-micrometer in size. It seems that the coalescence of nanovoids could lead to the formation of micro-voids in the structure of deformed samples.

  12. Construction and characterization of external cavity diode lasers for atomic physics.

    Science.gov (United States)

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-04-24

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

  13. Impact of dynamic specimen shape evolution on the atom probe tomography results of doped epitaxial oxide multilayers: Comparison of experiment and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Madaan, Nitesh; Nandasiri, Manjula; Devaraj, Arun, E-mail: arun.devaraj@pnnl.gov [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354 (United States); Bao, Jie [Energy and Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354 (United States); Xu, Zhijie [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354 (United States); Thevuthasan, Suntharampillai [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354 (United States); Qatar Environment and Energy Research Institute, Qatar Foundation, PO Box 5825, Doha (Qatar)

    2015-08-31

    The experimental atom probe tomography (APT) results from two different specimen orientations (top-down and sideways) of a high oxygen ion conducting Samaria-doped-ceria/Scandia-stabilized-zirconia multilayer thin film solid oxide fuel cell electrolyte was compared with level-set method based field evaporation simulations for the same specimen orientations. This experiment-simulation comparison explains the dynamic specimen shape evolution and ion trajectory aberrations that can induce density artifacts in final reconstruction, leading to inaccurate estimation of interfacial intermixing. This study highlights the importance of comparing experimental results with field evaporation simulations when using APT to study oxide heterostructure interfaces.

  14. Networking strategies of the microscopy community for improved utilization of advanced instruments: (2) The national network for transmission electron microscopy and atom probe studies in France (METSA)

    International Nuclear Information System (INIS)

    With the development, over the past ten years, of a new generation of electron microscopes with advanced performance, incorporating aberration correctors, monochromators, more sensitive detectors, and innovative specimen environments, quantitative measurements at the sub-nanometer and, in certain cases, at the unique atom level, are now accessible. However, an optimized use of these possibilities requires access to costly instruments and support by specialized trained experts. For these reasons, a national network (METSA) has been created in France with the support of CNRS and CEA in order to offer, in centres with complementary equipment and expertise, an open access to an enlarged and multidisciplinary community of academic and industrial users. The eight METSA platforms offer an access to 3 atom probes and 17 electron microscopes, mainly aberration-corrected TEMs, but also one dedicated environmental SEM and 3 double-column SEM-FIB

  15. Diffusion of hydrogen isotopes as a probe to study the atomic microstructure of metals. [Ni; CuAu; NiPt; FeZr

    Energy Technology Data Exchange (ETDEWEB)

    Hirscher, M.; Kronmueller, H. (Max-Planck-Inst. fuer Metallforschung, Inst. fuer Physik, Stuttgart (Germany))

    1991-08-30

    Magnetic after-effect measurements are very sensitive to short-range reorientation relaxations and represent an ideal tool for the study of hydrogen diffusion even at low concentrations. In this paper we deal with the interaction of hydrogen with defects or different microstructures and with the local reorientation in the vicinity of these structures. Results of hydrogen diffusion in a pure metal with radiation-induced intrinsic atomic defects, in chemically ordered and disordered binary f.c.c. alloys, and in chemically as well as structurally disordered amorphous alloys are presented. The three examples illustrate the use of hydrogen as an internal probe to detect microstructural defects on an atomic scale. (orig.).

  16. Combined nano-SIMS/AFM/EBSD analysis and atom probe tomography, of carbon distribution in austenite/ε-martensite high-Mn steels.

    Science.gov (United States)

    Seol, Jae-Bok; Lee, B-H; Choi, P; Lee, S-G; Park, C-G

    2013-09-01

    We introduce a new experimental approach for the identification of the atomistic position of interstitial carbon in a high-Mn binary alloy consisting of austenite and ε-martensite. Using combined nano-beam secondary ion mass spectroscopy, atomic force microscopy and electron backscatter diffraction analyses, we clearly observe carbon partitioning to austenite. Nano-beam secondary ion mass spectroscopy and atom probe tomography studies also reveal carbon trapping at crystal imperfections as identified by transmission electron microscopy. Three main trapping sites can be distinguished: phase boundaries between austenite and ε-martensite, stacking faults in austenite, and prior austenite grain boundaries. Our findings suggest that segregation and/or partitioning of carbon can contribute to the austenite-to-martensite transformation of the investigated alloy.

  17. Characterization of atomized extract of Opuntia ficusindica (L. Mill. and assessment of its pharmaceutical potential

    Directory of Open Access Journals (Sweden)

    Cinthya Maria Pereira Souza

    2014-04-01

    Full Text Available Given the many traditional uses of Opuntia ficus-indica (L. Mill. and the widespread employment of dry extracts in herbal medicine and phytocosmetics, the aim of this study is to characterize an atomized extract of O. ficus-indica cladodes, as well as to analyze its phytochemical composition and assay the total phenol content. In addition, the antioxidant, antimicrobial and photoprotective activities of the extract and its capacity to inhibit the enzyme tyrosinase were assessed, with a view to its pharmaceutical use. The physicochemical characterization was performed by pharmacopoeial tests, thermal analysis and infrared spectroscopy. Phytochemicals were analyzed by thin layer chromatography and total phenols by spectroscopy in the visible region. Antioxidant activity was detected by the method of free radical (DPPH● scavenging and antimicrobial activity by the agar diffusion method, while inhibition of tyrosinase was estimated by the diphenolase activity assay and photoprotective activity by a spectrophotometric method. The pharmacopeial tests, IR spectroscopy and thermal analysis enabled the atomized extract to be characterized. Concerning the potential for pharmaceutical use, it was found that, under the study conditions, the extract did not show any antioxidant, antimicrobial or photoprotective activity. However, it did show a modest tyrosinase inhibitory capacity. The originality of the proposed research on O. ficus-indica in the pharmaceutical field should be emphasized, as it opens new prospects for the study of a species that is so abundant and adapted to Brazilian semi-arid regions.

  18. Kelvin probe force microscopy for characterizing doped semiconductors for future sensor applications in nano- and biotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Heidemarie, E-mail: Heidemarie.Schmidt@etit.tu-chemnitz.de [Chemnitz University of Technology, Department of Materials for Nanoelectronics, Faculty of Electrical Engineering and Information Technology, 09126 Chemnitz (Germany); Habicht, Stefan; Feste, Sebastian [Forschungszentrum Jülich, Peter Grünberg Institute 9 (PGI-9-IT), 52425 Jülich (Germany); JARA-FIT, Fundamentals of Future Information Technology (Germany); Müller, Anne-Dorothea [Anfatec Instruments AG, Melanchthonstr. 28, 08606 Oelsnitz (Germany); Schmidt, Oliver G. [Chemnitz University of Technology, Department of Materials for Nanoelectronics, Faculty of Electrical Engineering and Information Technology, 09126 Chemnitz (Germany); Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden (Germany)

    2013-09-15

    Kelvin probe force microscopy (KPFM) is one of the most promising non-contact electrical nanometrology techniques to characterize doped semiconductors. By applying a recently introduced explanation of measured KPFM signals, we show the applicability of KPFM to determine and control surface-near electrostatic forces in planar doped silicon and in doped silicon nanostructures. Surface-near electrostatic forces may be used for the immobilization of nano- and biomaterials in future sensor applications in nano- and biotechnology. Additionally, the influence of the electrostatic potential distribution in doped semiconductor nanostructures, e.g. in horizontal Si nanowires, and its influence on the surface-near electrostatic forces are discussed. It is explained how drift and diffusion of injected electrons and holes in intrinsic electric fields influence the detected KPFM signal. For example KPFM is successfully employed to locate p{sup +}p and n{sup +}p junctions along B-doped and As-doped p-Si nanowires, respectively. As an outlook the physical immobilization and the transport of biomaterials above arrays of separately addressable doped semiconductor cells will be discussed.

  19. Kelvin probe force microscopy for characterizing doped semiconductors for future sensor applications in nano- and biotechnology

    Science.gov (United States)

    Schmidt, Heidemarie; Habicht, Stefan; Feste, Sebastian; Müller, Anne-Dorothea; Schmidt, Oliver G.

    2013-09-01

    Kelvin probe force microscopy (KPFM) is one of the most promising non-contact electrical nanometrology techniques to characterize doped semiconductors. By applying a recently introduced explanation of measured KPFM signals, we show the applicability of KPFM to determine and control surface-near electrostatic forces in planar doped silicon and in doped silicon nanostructures. Surface-near electrostatic forces may be used for the immobilization of nano- and biomaterials in future sensor applications in nano- and biotechnology. Additionally, the influence of the electrostatic potential distribution in doped semiconductor nanostructures, e.g. in horizontal Si nanowires, and its influence on the surface-near electrostatic forces are discussed. It is explained how drift and diffusion of injected electrons and holes in intrinsic electric fields influence the detected KPFM signal. For example KPFM is successfully employed to locate p+p and n+p junctions along B-doped and As-doped p-Si nanowires, respectively. As an outlook the physical immobilization and the transport of biomaterials above arrays of separately addressable doped semiconductor cells will be discussed.

  20. Kelvin probe characterization of buried graphitic microchannels in single-crystal diamond

    Science.gov (United States)

    Bernardi, E.; Battiato, A.; Olivero, P.; Picollo, F.; Vittone, E.

    2015-01-01

    In this work, we present an investigation by Kelvin Probe Microscopy (KPM) of buried graphitic microchannels fabricated in single-crystal diamond by direct MeV ion microbeam writing. Metal deposition of variable-thickness masks was adopted to implant channels with emerging endpoints and high temperature annealing was performed in order to induce the graphitization of the highly-damaged buried region. When an electrical current was flowing through the biased buried channel, the structure was clearly evidenced by KPM maps of the electrical potential of the surface region overlying the channel at increasing distances from the grounded electrode. The KPM profiling shows regions of opposite contrast located at different distances from the endpoints of the channel. This effect is attributed to the different electrical conduction properties of the surface and of the buried graphitic layer. The model adopted to interpret these KPM maps and profiles proved to be suitable for the electronic characterization of buried conductive channels, providing a non-invasive method to measure the local resistivity with a micrometer resolution. The results demonstrate the potential of the technique as a powerful diagnostic tool to monitor the functionality of all-carbon graphite/diamond devices to be fabricated by MeV ion beam lithography.

  1. Interior Characterization of Europa using Magnetometry (ICEMAG): Probing the Europan Ocean and Exosphere

    Science.gov (United States)

    Raymond, C. A.; Jia, X.; Joy, S. P.; Khurana, K. K.; Murphy, N.; Russell, C. T.; Strangeway, R. J.; Weiss, B. P.

    2015-12-01

    Magnetic induction is a powerful tool for probing the subsurface. The magnetometer on the Galileo mission to Jupiter found compelling evidence for subsurface oceans on Europa, Ganymede and Callisto; however, the single induction frequency measured did not allow characteristics of the ocean to be discerned. The Interior Characterization of Europa using MAGnetometry (ICEMAG) instrument, selected for NASA's Europa mission payload in May 2015, is designed to measure Europa's induction response at multiple frequencies with high accuracy. ICEMAG definitively assesses the ice shell thickness, and the conductivity and thickness of the subsurface ocean. This knowledge informs models of Europa's thermal evolution and allows evaluation of processes that have cycled material between the depths and the surface. Magnetic field measurements also determine the electrical currents associated with coupling of plumes to the corotating magnetospheric plasma and coupling of Europa to the Jovian ionosphere. ICEMAG utilizes UCLA fluxgate magnetic field sensors as well as JPL helium sensors in an integrated magnetic measurement system. The advent of laser-pumped helium sensors and advances in digital signal sampling enables an innovative multi-sensor magnetometer to be flown that is able to monitor spacecraft fields and maintain absolute accuracy of the measurement at a level of ~1 nT over time scales of years, without special maneuvers such as spacecraft rolls.

  2. Robotic arm design for a remotely-deployed, in situ waste characterization probe

    International Nuclear Information System (INIS)

    This paper describes some design considerations for a system which will combine robotics and laser spectroscopy to produce an in situ monitoring system for heterogeneous waste materials. The new system will provide faster, cheaper, safer, and more complete characterization of mixed solids and liquids stored in tanks and drums or buried in pits. A small, fiberoptic multiprobe that performs Raman and fluorescence measurements of wastes composed of a variety of organic and inorganic compounds will be described. Design considerations for a novel sensor platform that positions and stabilizes the multiprobe relative to the sampling point in order to make accurate spectroscopic measurements and deploys the sensor in hazardous environments with minimal risk to workers will be presented. The core of the platform will be a 3-Degrees-Of-Freedom (3-DOF), spherical coordinate end effector equipped with a proximity sensor that compensates for errors introduced by the flexible nature of the support arm. The platform can be adapted to operate the most robotic deployment systems used in hazardous environments. The multisensor probe will be coupled to remote, portable laser spectrometer systems by a fiber-optic bundle. 5 refs

  3. Design, synthesis, and characterization of novel nanowire structures for photovoltaics and intracellular probes.

    Science.gov (United States)

    Tian, Bozhi; Lieber, Charles M

    2011-01-01

    Semiconductor nanowires (NWs) represent a unique system for exploring phenomena at the nanoscale and are expected to play a critical role in future electronic, optoelectronic, and miniaturized biomedical devices. Modulation of the composition and geometry of nanostructures during growth could encode information or function, and realize novel applications beyond the conventional lithographical limits. This review focuses on the fundamental science aspects of the bottom-up paradigm, which are synthesis and physical property characterization of semiconductor NWs and NW heterostructures, as well as proof-of-concept device concept demonstrations, including solar energy conversion and intracellular probes. A new NW materials synthesis is discussed and, in particular, a new "nanotectonic" approach is introduced that provides iterative control over the NW nucleation and growth for constructing 2D kinked NW superstructures. The use of radial and axial p-type/intrinsic/n-type (p-i-n) silicon NW (Si-NW) building blocks for solar cells and nanoscale power source applications is then discussed. The critical benefits of such structures and recent results are described and critically analyzed, together with some of the diverse challenges and opportunities in the near future. Finally, results are presented on several new directions, which have recently been exploited in interfacing biological systems with NW devices.

  4. Preparation and characterization of a magnetic and optical dual-modality molecular probe

    Energy Technology Data Exchange (ETDEWEB)

    Bumb, A; Brechbiel, M W [Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, NCI, NIH, Building 10, Room 1B53, 10 Center Drive, Bethesda, MD 20892 (United States); Regino, C A S; Ogawa, M; Choyke, P L [Molecular Imaging Program, NCI, NIH, Building 10, Room B3B69, 10 Center Drive, Bethesda, MD 20892 (United States); Perkins, M R [Vaccine Research Center, NIAID, NIH, Building 40, Room 3608B, 40 Convent Drive, Bethesda, MD 20892 (United States); Bernardo, M [SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702 (United States); Fugger, L [MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, The University of Oxford, Oxford OX3 9DS (United Kingdom); Dobson, P J, E-mail: Bumba@mail.nih.gov, E-mail: martinwb@mail.nih.gov [Oxford University Begbroke Science Park, Sandy Lane, Kidlington, Oxon OX5 1PF (United Kingdom)

    2010-04-30

    Multi-modality imaging probes combine the advantages of individual imaging techniques to yield highly detailed anatomic and molecular information in living organisms. Herein, we report the synthesis and characterization of a dual-modality nanoprobe that couples the magnetic properties of ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) with the near infrared fluorescence of Cy5.5. The fluorophore is encapsulated in a biocompatible shell of silica surrounding the iron oxide core for a final diameter of {approx} 17 nm. This silica-coated iron oxide nanoparticle (SCION) has been analyzed by transmission electron microscopy, dynamic light scattering, and superconducting quantum interference device (SQUID). The particle demonstrates a strong negative surface charge and maintains colloidal stability in the physiological pH range. Magnetic hysteresis analysis confirms superparamagnetic properties that could be manipulated for thermotherapy. The viability of primary human monocytes, T cells, and B cells incubated with the particle has been examined in vitro. In vivo analysis of agent leakage into subcutaneous A431 tumors in mice was also conducted. This particle has been designed for diagnostic application with magnetic resonance and fluorescence imaging, and has future potential to serve as a heat-sensitive targeted drug delivery platform.

  5. Optical Characterization of a Hollow Fiber Raman Probe toward Non-Invasive Measurements of Living Tissues

    Science.gov (United States)

    Mitsuoka, Hiroki; Morita, Shin-ichi; Suzuki, Toshiaki; Matsuura, Yuji; Katsumoto, Yukiteru; Sato, Hidetoshi

    2009-02-01

    The use of a hollow fiber as a Raman probe, which gives strong advantage of a free link in space, was confirmed to be a versatile and standard analytical method, since Raman data obtained through a hollow fiber probe assures a sufficient link to conventional Raman data. In this paper, we confirmed that a Raman spectrum given by the hollow fiber probe becomes identical to a Raman spectrum measured by a conventional approach, if one is multiplied by an optimized coefficient. In addition, Raman signal intensity changes were related to various types of curved geometries of the probe. The Raman signal intensity value at a curved geometry of the probe, which is one of the most frequently used positions, became 0.35 compared to the value at the standard position of the probe (straight lined).

  6. Synthesis and Characterization of a Novel β-cyclodextrin Fluorescent Probe

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Introduction In recent years, new development for the fluorescent chemical sensor has made the method and application of fluorescent probes been greatly enhanced and extended fully. Fluorescent probes has important value not only in research of pharmacology and physiology, but also has made great contribution in environmental science, information science etc.Cyclodextrin modified by fluorescence group as a spectral probe in supramolecular chemistry has important applications, and Japan's Ueno researc...

  7. Novel thin membrane probe and a new twisting modulation force detection method of an atomic force microscope

    Science.gov (United States)

    Nakano, Katsushi; Suzuki, Yoshihiko

    1999-04-01

    For inspection of high aspect ratio structures like narrow semiconductor trenches, a thin membrane probe and a new force detection method have been proposed. Instead of conventional conical and pyramidal tips, a thin silicon nitride cantilever was set up vertically, and its edge was used as a tip. The membrane probe named as twist-probe (TP) was oscillated in the twisting resonance to detect a force from both vertical and lateral directions. About 100 μm long, 0.7 μm thick TP was fabricated as a trial. Amplitude versus distance curve measurements showed that the TP has a high spacing change sensitivity between the tip and a sample in both vertical and lateral directions. A trench cross-section imaging was demonstrated successfully with a TP and the twist resonant force detection method.

  8. Four-probe scanning tunnelling microscope with atomic resolution for electrical and electro-optical property measurements of nanosystems

    Institute of Scientific and Technical Information of China (English)

    Lin Xiao; He Xiao-Bo; Lu Jun-Ling; Gao Li; Huan Qing; Shi Dong-Xia; Gao Hong-Jun

    2005-01-01

    We demonstrate a special four-probe scanning tunnelling microscope (STM) system in ultrahigh vacuum (UHV),which can provide coarse positioning for every probe independently with the help of scanning electron microscope (SEM)and fine positioning down to nanometre using the STM technology. The system allows conductivity measurement by means of a four-point probe method, which can draw out more accurate electron transport characteristics in nanostructures, and provides easy manipulation of low dimension materials. All measurements can be performed in variable temperature (from 30K to 500K), magnetic field (from 0 to 0.1T), and different gas environments. Simultaneously, the cathodoluminescence (CL) spectrum can be achieved through an optical subsystem. Test measurements using some nanowire samples show that this system is a powerful tool in exploring electron transport characteristics and spectra in nanoscale physics.

  9. Application of scanning Kelvin probe microscopy for the electrical characterization of microcrystalline silicon for photovoltaics

    International Nuclear Information System (INIS)

    In the last years microcrystalline silicon thin films have attracted great attention as a new photovoltaic material. With this material it is possible to combine simple and cheap low temperature deposition techniques known from amorphous silicon with the long-term stability of the photovoltaic performance like in bulk crystalline silicon solar cells. The critical point is the deposition procedure with numerous tunable parameters influencing the quality and character of the produced diode structures. Additionally there is a great uncertainty about unintentionally incorporated defects, which is not affected by the deposition parameters. Extended investigation of the material, diode and solar cell characteristics is essential in order to correlate the impact of deposition conditions with the quality of the devices. The situation is complicated due to the anisotropic and inhomogeneous character of microcrystalline silicon. Scanning Kelvin probe microscopy (SKPM) is a work function measurement method based on a scanning force microscope (SFM) and a modified Kelvin probe technique. Due to the excellent lateral resolution of the SFM work function measurements with resolutions far below the micrometer level can be carried out. Applied on doped microcrystalline silicon structures it is possible to visualize the position of the Fermi level within the band gap and the influence of the deposition conditions on it. Within this work a SKPM based on a commercially available SFM was constructed and built. Great effort was concentrated on the characterization of the SKPM experiment. On the basis of an extended knowledge about the performance investigations concentrated on cross sections of microcrystalline silicon diode structures produced by hot-wire chemical vapor deposition (HW-CVD). A pin structure for the diodes was chosen due to the low diffusion lengths within this rather defective material. The evolution of the built-in electric drift field within the intrinsic absorber is

  10. Electrical characterization of electron beam induced damage on sub-10 nm n-channel MOS transistors using nano-probing technique

    Science.gov (United States)

    Kang, Jonghyuk; Lee, Sungho; Choi, Byoungdeog

    2016-11-01

    Electron beam induced damage on sub-10 nm n-channel MOS transistors was evaluated using an atomic force microscopy-based nano-probing technique. After electron beam irradiation, all the device parameters shifted including threshold voltage (V th), saturation current, sub-threshold slope and transistor leakage current. A negative shift in V th occurred at low electron beam acceleration voltage (V acc) because of the increase in oxide trapped holes generated by excited plasmons. At high V acc, however, a positive V th shift was observed because of an increased contribution of interface trap generation caused by the deeper electron penetration depth. In addition, interface trap generation not only degraded the sub-threshold slope due to the additional capacitance from the generated interface traps, but also increased transistor leakage current due to changes in junction characteristics. Our studies show that it is critical to avoid electron beam exposure before electrical characterization on sub-10 nm devices even in the range of less than 1.0 kV of V acc using nano-probe systems.

  11. Using Downhole Probes to Locate and Characterize Buried Transuranic and Mixed Low Level Waste

    Energy Technology Data Exchange (ETDEWEB)

    Steinman, Donald K; Bramblett, Richard L; Hertzog, Russel C

    2012-06-25

    Borehole logging probes were developed and tested to locate and quantify transuranic elements in subsurface disposal areas and in contaminated sites at USDOE Weapons Complex sites. A new method of measuring very high levels of chlroine in the subsurface was developed using pulsed neutron technology from oilfield applications. The probes were demonstrated at the Hanford site in wells containing plutonium and other contaminants.

  12. Development of Simple Designs of Multitip Probe Diagnostic Systems for RF Plasma Characterization

    Directory of Open Access Journals (Sweden)

    M. Y. Naz

    2014-01-01

    Full Text Available Multitip probes are very useful diagnostics for analyzing and controlling the physical phenomena occurring in low temperature discharge plasmas. However, DC biased probes often fail to perform well in processing plasmas. The objective of the work was to deduce simple designs of DC biased multitip probes for parametric study of radio frequency plasmas. For this purpose, symmetric double probe, asymmetric double probe, and symmetric triple probe diagnostic systems and their driving circuits were designed and tested in an inductively coupled plasma (ICP generated by a 13.56 MHz radio frequency (RF source. Using I-V characteristics of these probes, electron temperature, electron number density, and ion saturation current was measured as a function of input power and filling gas pressure. An increasing trend was noticed in electron temperature and electron number density for increasing input RF power whilst a decreasing trend was evident in these parameters when measured against filling gas pressure. In addition, the electron energy probability function (EEPF was also studied by using an asymmetric double probe. These studies confirmed the non-Maxwellian nature of the EEPF and the presence of two groups of the energetic electrons at low filling gas pressures.

  13. Microstructural analysis of impurity segregation around β-Nb precipitates in Zr–Nb alloy using positron annihilation spectroscopy and atom probe tomography

    International Nuclear Information System (INIS)

    Graphical abstract: Fe segregation are evident at the interface between β-Nb precipitates and α-Zr matrix by atom probe tomography (APT). Defects are observed at the interface by positron annihilation spectroscopy. It is also suggested that Fe was segregated to a concentration of several tens of percent at a local region at the interface, which is approximately one order of magnitude higher than APT and difficult to observe directly even using APT. - Abstract: Impurity segregation at the interface between β-Nb precipitates and α-Zr matrix in Zr-2.5 wt.%Nb alloy was investigated by complementary analysis with positron annihilation spectroscopy (PAS) and atom probe tomography (APT). Fe segregation and Fe-decorated defects were found at the interface. PAS also suggested that Fe was segregated to a concentration of several tens of percent at a local region at the interface, which is approximately one order of magnitude higher than APT and difficult to observe directly even using APT

  14. Development of Neutron Probes for Characterization of Hazardous Materials in the Sub-surface Medium

    International Nuclear Information System (INIS)

    Neutron probes are being developed at the Idaho National Engineering and Environmental Laboratory (INEEL) for the detection, identification and quantification of hazardous materials in the ground. Such materials include plutonium, uranium, americium, chlorine and fluorine. Both a Neutron Gamma (NG) probe and a Prompt Fission Neutron (PFN) probe are being developed. The NG probe is used primarily for nuclide identification and quantification measurements. The PFN is used mostly for the detection and measurement of fissile material, but also for the determination of thermal neutron macroscopic absorption cross sections of the various elements comprising the ground matrix. Calibration of these probes will be carried out at the INEEL using an indoor facility that has been designed for this activity

  15. Frequency Methods Applied to the Characterization of the Thermophysical Properties of a Granular Material with a Cylindrical Probe

    Science.gov (United States)

    Carpentier, Olivier; Defer, Didier; Antczak, Emmanuel; Chartier, Thierry

    2012-01-01

    In many fields, such as in the agri-food industry or in the building industry, it is important to be able to monitor the thermophysical properties of granular materials. Regular thermal probes allow for the determination of one or several thermophysical factors. The success of the method used depends in part on the nature of the signal sent, on the type of physical model applied and eventually on the type of probe used and its implantation in the material. Although efficacious for most applications, regular thermal probes do present some limitations. It is the case, for example, when one has to know precisely the thermal contact resistance or the nature of the signal sent. In this article is presented a characterization method based on thermal impedance formalism. This method allows for the determination of the thermal conductivity, the thermal diffusivity, and the contact thermal resistance in one single test. The application of this method requires the use of a specific probe developed to enable measurement of heat flux and temperature at the interface of the probe and the studied material. Its practical application is presented for dry sand.

  16. Contribution to the physical modeling of the actinide characterization by electron probe microanalysis

    International Nuclear Information System (INIS)

    Electron probe microanalysis (EPMA) is used to quantify with a high accuracy the amount of different elements present on a sample of unknown composition. EPMA is largely used to quantify the amount of actinides present in fresh and irradiated fuels, to manage waste disposal and to date rocks. However, quantitative EPMA is not always possible to achieve for these materials due to the lack of suitable reference standards for the radionuclides. To overcome this difficulty, standard-less methods of analysis are employed with mean of virtual calculated standards. These calculated standards are generally obtained from empirical formulae based on experimental extrapolations or from theoretical calculations that require physical parameters which are poorly known as it is the case for the X-ray production cross section. The accurate knowledge of these cross sections is required in many applications such as in particle transport code and in Monte Carlo simulations. The computer simulations are widely used in the medical field and particularly in medical imaging and in electron beam therapy. In the field of astronomy, these data are used to perform simulations that predict the compositions of stars and galactic clouds, and the formation of planetary systems. In the present work, L- and M-shell absolute x-ray production cross sections were determined experimentally for elements lead, thorium and uranium by electron impact using ultrathin self-supporting targets with thickness varying from 0.2 to 8 nm. The measured cross sections have been compared, with the distorted-wave Born approximation (DWBA) calculated by Bote et al. and with the predictions of analytical formulae widely used in practical applications. For the conversion of inner-shell ionization cross sections into x-ray production cross sections, atomic relaxation parameters were extracted from the literature. The predictions of the DWBA calculations are in excellent agreement with our measured x-ray production cross

  17. Design and characterization of a novel multimodal fiber-optic probe and spectroscopy system for skin cancer applications

    Science.gov (United States)

    Sharma, Manu; Marple, Eric; Reichenberg, Jason; Tunnell, James W.

    2014-08-01

    The design and characterization of an instrument combining Raman, fluorescence, and reflectance spectroscopic modalities is presented. Instrument development has targeted skin cancer applications as a novel fiber-optic probe has been specially designed to interrogate cutaneous lesions. The instrument is modular and both its software and hardware components are described in depth. Characterization of the fiber-optic probe is also presented, which details the probe's ability to measure diagnostically important parameters such as intrinsic fluorescence and absorption and reduced scattering coefficients along with critical performance metrics such as high Raman signal-to-noise ratios at clinically practical exposure times. Validation results using liquid phantoms show that the probe and system can extract absorption and scattering coefficients with less than 10% error. As the goal is to use the instrument for the clinical early detection of skin cancer, preliminary clinical data are also presented, which indicates our system's ability to measure physiological quantities such as relative collagen and nicotinamide adenine dinucleotide concentration, oxygen saturation, blood volume fraction, and mean vessel diameter.

  18. Design and characterization of a novel multimodal fiber-optic probe and spectroscopy system for skin cancer applications.

    Science.gov (United States)

    Sharma, Manu; Marple, Eric; Reichenberg, Jason; Tunnell, James W

    2014-08-01

    The design and characterization of an instrument combining Raman, fluorescence, and reflectance spectroscopic modalities is presented. Instrument development has targeted skin cancer applications as a novel fiber-optic probe has been specially designed to interrogate cutaneous lesions. The instrument is modular and both its software and hardware components are described in depth. Characterization of the fiber-optic probe is also presented, which details the probe's ability to measure diagnostically important parameters such as intrinsic fluorescence and absorption and reduced scattering coefficients along with critical performance metrics such as high Raman signal-to-noise ratios at clinically practical exposure times. Validation results using liquid phantoms show that the probe and system can extract absorption and scattering coefficients with less than 10% error. As the goal is to use the instrument for the clinical early detection of skin cancer, preliminary clinical data are also presented, which indicates our system's ability to measure physiological quantities such as relative collagen and nicotinamide adenine dinucleotide concentration, oxygen saturation, blood volume fraction, and mean vessel diameter. PMID:25173240

  19. Combined Atomic Force Microscope-Based Topographical Imaging and Nanometer Scale Resolved Proximal Probe Thermal Desorption/Electrospray Ionization-Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikova, Olga S [ORNL; Nikiforov, Maxim [ORNL; Bradshaw, James A [ORNL; Jesse, Stephen [ORNL; Van Berkel, Gary J [ORNL

    2011-01-01

    Nanometer scale proximal probe thermal desorption/electrospray ionization mass spectrometry (TD/ESI-MS) was demonstrated for molecular surface sampling of caffeine from a thin film using a 30 nm diameter nano-thermal analysis (nano-TA) probe tip in an atomic force microscope (AFM) coupled via a vapor transfer line and ESI interface to a MS detection platform. Using a probe temperature of 350 C and a spot sampling time of 30 s, conical desorption craters 250 nm in diameter and 100 nm deep were created as shown through subsequent topographical imaging of the surface within the same system. Automated sampling of a 5 x 2 array of spots, with 2 m spacing between spots, and real time selective detection of the desorbed caffeine using tandem mass spectrometry was also demonstrated. Estimated from the crater volume (~2x106 nm3), only about 10 amol (2 fg) of caffeine was liberated from each thermal desorption crater in the thin film. These results illustrate a relatively simple experimental setup and means to acquire in automated fashion sub-micrometer scale spatial sampling resolution and mass spectral detection of materials amenable to TD. The ability to achieve MS-based chemical imaging with 250 nm scale spatial resolution with this system is anticipated.

  20. Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and radical polymerization

    Indian Academy of Sciences (India)

    Dhruba Jyoti Haloi; Bishnu Prasad Koiry; Prithwiraj Mandal; Nikhil Kumar Singha

    2013-07-01

    This investigation reports a comparative study of poly(2-ethylhexyl acrylate) (PEHA) prepared via atom transfer radical polymerization (ATRP), reverse atom transfer radical polymerization (RATRP) and conventional free radical polymerization (FRP). The molecular weights and the molecular weight distributions of the polymers were measured by gel permeation chromatography (GPC) analysis. Structural characterization of the polymers was carried out by 1H NMR and MALDI-TOF-MS analyses. Thermal properties of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymerization results and the thermal properties of PEHAs prepared via ATRP, RATRP and FRP were compared.

  1. Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry.

    Science.gov (United States)

    Canovic, Elizabeth Peruski; Qing, Bo; Mijailovic, Aleksandar S; Jagielska, Anna; Whitfield, Matthew J; Kelly, Elyza; Turner, Daria; Sahin, Mustafa; Van Vliet, Krystyn J

    2016-01-01

    To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain tissue itself must be well characterized at various length and time scales. Like many biological tissues, brain tissue exhibits a complex, hierarchical structure. However, in contrast to most other tissues, brain is of very low mechanical stiffness, with Young's elastic moduli E on the order of 100s of Pa. This low stiffness can present challenges to experimental characterization of key mechanical properties. Here, we demonstrate several mechanical characterization techniques that have been adapted to measure the elastic and viscoelastic properties of hydrated, compliant biological materials such as brain tissue, at different length scales and loading rates. At the microscale, we conduct creep-compliance and force relaxation experiments using atomic force microscope-enabled indentation. At the mesoscale, we perform impact indentation experiments using a pendulum-based instrumented indenter. At the macroscale, we conduct parallel plate rheometry to quantify the frequency dependent shear elastic moduli. We also discuss the challenges and limitations associated with each method. Together these techniques enable an in-depth mechanical characterization of brain tissue that can be used to better understand the structure of brain and to engineer bio-inspired materials. PMID:27684097

  2. Characterization of Atomic and Electronic Structures of Electrochemically Active SOFC Cathode Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Blinn; Yongman Choi; Meilin Liu

    2009-08-11

    The objective of this project is to gain a fundamental understanding of the oxygen-reduction mechanism on mixed conducting cathode materials by means of quantum-chemical calculations coupled with direct experimental measurements, such as vibrational spectroscopy. We have made progress in the elucidation of the mechanisms of oxygen reduction of perovkite-type cathode materials for SOFCs using these quantum chemical calculations. We established computational framework for predicting properties such as oxygen diffusivity and reaction rate constants for adsorption, incorporation, and TPB reactions, and formulated predictions for LSM- and LSC-based cathode materials. We have also further developed Raman spectroscopy as well as SERS as a characterization tool for SOFC cathode materials. Raman spectroscopy was used to detect chemical changes in the cathode from operation conditions, and SERS was used to probe for pertinent adsorbed species in oxygen reduction. However, much work on the subject of unraveling oxygen reduction for SOFC cathodes remains to be done.

  3. Multiple-probe scanning probe microscopes for nanoarchitectonic materials science

    Science.gov (United States)

    Nakayama, Tomonobu; Shingaya, Yoshitaka; Aono, Masakazu

    2016-11-01

    Nanoarchitectonic systems are of interest for utilizing a vast range of nanoscale materials for future applications requiring a huge number of elemental nanocomponents. To explore the science and technology of nanoarchitectonics, advanced characterization tools that can deal with both nanoscale objects and macroscopically extended nanosystems are demanded. Multiple-probe scanning probe microscopes (MP-SPMs) are powerful tools that meet this demand because they take the advantages of conventional scanning probe microscopes and realize atomically precise electrical measurements, which cannot be done with conventional microprobing systems widely used in characterizing materials and devices. Furthermore, an MP-SPM can be used to operate some nanoarchitectonic systems. In this review, we overview the indispensable features of MP-SPMs together with the past, present and future of MP-SPM technology.

  4. Distribution of Cold ($\\lesssim 300$K) Atomic Gas in Galaxies: Results from the GBT HI Absorption Survey Probing the Inner Halos ($\\rho<20$kpc) of Low-z Galaxies

    CERN Document Server

    Borthakur, Sanchayeeta

    2016-01-01

    We present the Green Bank Telescope absorption survey of cold atomic hydrogen ($\\lesssim 300$K) in the inner halo of low-redshift galaxies. The survey aims to characterize the cold gas distribution and to address where condensation - the process where ionized gas accreted by galaxies condenses into cold gas within the disks of galaxies - occurs. Our sample consists of 16 galaxy-quasar pairs with impact parameters of $\\le$ 20kpc. We detected an HI absorber associated with J0958+3222 (NGC 3067) and HI emission from six galaxies. We also found two \\ion{Ca}{2} absorption system in the archival SDSS data associated with galaxies J0958+3222 and J1228+3706, although the sample was not selected based on the presence of metals in absorption. Our detection rate of HI absorbers with optical depths of $\\ge 0.06$ is $\\sim$7\\%. We also find that cold HI phase ($\\lesssim$300K) is 44($\\pm$18)\\% of the total atomic gas in the sightline probing J0958+3222. We find no correlation between the peak optical depth and impact parame...

  5. Ordering and site occupancy of D03 ordered Fe3Al-5 at%Cr evaluated by means of atom probe tomography

    International Nuclear Information System (INIS)

    Addition of ternary elements to the D03 ordered Fe3Al intermetallic phase is a general approach to optimise its mechanical properties. To understand the physical influences of such additions the determination of the probability of site occupancies of these additions on the lattice site and ordering parameters is of high interest. Some common experimental techniques such as X-ray diffraction or Atom Location by Channelling Enhanced Microanalysis (ALCHEMI) are usually applied to explore this interplay. Unfortunately, certain published results are partly inconsistent, imprecise or even contradictory. In this study, these aspects are evaluated systematically by atom probe tomography (APT) and a special data analysis method. Additionally, to account for possible field evaporation effects that can falsify the estimation of site occupancy and induce misinterpretations, APT evaporation sequences were also simulated. As a result, chromium occupies most frequently the next nearest neighbour sites of Al atoms and local ordering parameters could be achieved. -- Research highlights: → APT measurements of Fe3Al-Cr are systematically analysed to study ordering. → APT measurements are simulated using EAM to calculate binding energies. → Cr occupies next nearest neighbour sites of aluminium with at least 83% ordering. → Aluminium ordering is at least 92%

  6. An optical fiber-taper probe for wafer-scale microphotonic device characterization

    OpenAIRE

    Michael, C. P.; Borselli, M; Johnson, T. J.; Chrystal, C; Painter, O.

    2007-01-01

    A small depression is created in a straight optical fiber taper to form a local probe suitable for studying closely spaced, planar microphotonic devices. The tension of the "dimpled" taper controls the probe-sample interaction length and the level of noise present during coupling measurements. Practical demonstrations with high-Q silicon microcavities include testing a dense array of undercut microdisks (maximum Q = 3.3x10^6) and a planar microring (Q = 4.8x10^6).

  7. An optical fiber-taper probe for wafer-scale microphotonic device characterization

    CERN Document Server

    Michael, C P; Johnson, T J; Chrystal, C; Painter, O; 10.1364/OE.15.004745

    2009-01-01

    A small depression is created in a straight optical fiber taper to form a local probe suitable for studying closely spaced, planar microphotonic devices. The tension of the "dimpled" taper controls the probe-sample interaction length and the level of noise present during coupling measurements. Practical demonstrations with high-Q silicon microcavities include testing a dense array of undercut microdisks (maximum Q = 3.3x10^6) and a planar microring (Q = 4.8x10^6).

  8. Generating and characterizing the mechanical properties of cell-derived matrices using atomic force microscopy.

    Science.gov (United States)

    Tello, Marta; Spenlé, Caroline; Hemmerlé, Joseph; Mercier, Luc; Fabre, Roxane; Allio, Guillaume; Simon-Assmann, Patricia; Goetz, Jacky G

    2016-02-01

    Mechanical interaction between cells and their surrounding extracellular matrix (ECM) controls key processes such as proliferation, differentiation and motility. For many years, two-dimensional (2D) models were used to better understand the interactions between cells and their surrounding ECM. More recently, variation of the mechanical properties of tissues has been reported to play a major role in physiological and pathological scenarios such as cancer progression. The 3D architecture of the ECM finely tunes cellular behavior to perform physiologically relevant tasks. Technical limitations prevented scientists from obtaining accurate assessment of the mechanical properties of physiologically realistic matrices. There is therefore a need for combining the production of high-quality cell-derived 3D matrices (CDMs) and the characterization of their topographical and mechanical properties. Here, we describe methods that allow to accurately measure the young modulus of matrices produced by various cellular types. In the first part, we will describe and review several protocols for generating CDMs matrices from endothelial, epithelial, fibroblastic, muscle and mesenchymal stem cells. We will discuss tools allowing the characterization of the topographical details as well as of the protein content of such CDMs. In a second part, we will report the methodologies that can be used, based on atomic force microscopy, to accurately evaluate the stiffness properties of the CDMs through the quantification of their young modulus. Altogether, such methodologies allow characterizing the stiffness and topography of matrices deposited by the cells, which is key for the understanding of cellular behavior in physiological conditions.

  9. Characterization of deep nanoscale surface trenches with AFM using thin carbon nanotube probes in amplitude-modulation and frequency-force-modulation modes

    Science.gov (United States)

    Solares, Santiago D.

    2008-01-01

    The characterization of deep surface trenches with atomic force microscopy (AFM) presents significant challenges due to the sharp step edges that disturb the instrument and prevent it from faithfully reproducing the sample topography. Previous authors have developed AFM methodologies to successfully characterize semiconductor surface trenches with dimensions on the order of tens of nanometers. However, the study of imaging fidelity for features with dimensions smaller than 10 nm has not yet received sufficient attention. Such a study is necessary because small features in some cases lead to apparently high-quality images that are distorted due to tip and sample mechanical deformation. This paper presents multi-scale simulations, illustrating common artifacts affecting images of nanoscale trenches taken with fine carbon nanotube probes within amplitude-modulation and frequency-force-modulation AFM (AM-AFM and FFM-AFM, respectively). It also describes a methodology combining FFM-AFM with a step-in/step-out algorithm analogous to that developed by other groups for larger trenches, which can eliminate the observed artifacts. Finally, an overview of the AFM simulation methods is provided. These methods, based on atomistic and continuum simulation, have been previously used to study a variety of samples including silicon surfaces, carbon nanotubes and biomolecules.

  10. Probing the Structure and Chemistry of Perylenetetracarboxylic Dianhydride on Graphene Before and After Atomic Layer Deposition of Alumina

    OpenAIRE

    Johns, James E.; Karmel, Hunter J.; Alaboson, Justice M. P.; Hersam, Mark C.

    2012-01-01

    The superlative electronic properties of graphene suggest its use as the foundation of next generation integrated circuits. However, this application requires precise control of the interface between graphene and other materials, especially the metal oxides that are commonly used as gate dielectrics. Towards that end, organic seeding layers have been empirically shown to seed ultrathin dielectric growth on graphene via atomic layer deposition (ALD), although the underlying chemical mechanisms...

  11. Probing Co/Si interface behaviour by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this work, we investigate the Co-Si reaction, the Co growth mode at room temperature, diffusion behaviour as well as morphology evolution during annealing on both H-terminated and clean Si(001) and Si(111) surfaces. From in-situ X-ray photoelectron spectroscopy (XPS) investigation, "Co-Si" reaction appears to occur on both H-terminated and clean surfaces at room temperature (RT) and the silicide crystallinity is improved upon annealing.Co growth mode on H-terminated Si surfaces occurs in a pseudo layer-by-layer manner while small close-packed island growth mode is observed on the clean Si surface. Upon annealing at different temperatures, Co atom concentration decreases versus annealing time, which in part is attributed to Co atoms inward diffusion. The diffusion behaviour on both types of surfaces demonstrates a similar trend. Morphology study using ex-situ atomic force microscopy (AFM) shows that the islands formed on Si(001) surface after annealing at 700 ℃ are elongated with growth directions alternate between the two perpendicular [(-1)10] and [110] directions. Triangular islands are observed on Si(111) surface.

  12. Parallel scanning probe arrays: their applications

    Directory of Open Access Journals (Sweden)

    Chang Liu

    2008-01-01

    Full Text Available Since the invention of the scanning tunneling microscope (STM1 and the atomic force microscope (AFM2, the field of scanning probe microscopy (SPM instruments has grown steadily and has had a profound influence in materials research, chemistry, biology, nanotechnology, and electronics3,4. Today, scanning probe instruments are used for metrology, characterization5, detection6, manipulation7, patterning8,9, and material modification. A wide range of scanning probe applications are available, taking advantage of various modes of tip–substrate interactions, including force, optics10,11, electrochemistry12, electromagnetics, electrostatics, thermal and mass transfer13,14, and vibration15,16.

  13. Nanotribological characterization of digital micromirror devices using an atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Liu Huiwen; Bhushan, Bharat

    2004-08-15

    Texas Instruments' digital micromirror device (DMD) comprises an array of fast digital micromirrors, monolithically integrated onto and controlled by an underlying silicon memory chip. The DMD is one of the few success stories in the emerging field of MEMS. In this study, an atomic force microscope (AFM) has been used to characterize the nanotribological properties of the elements of the DMD. An AFM methodology was developed to identify and remove micromirrors of interest. The surface roughness, adhesion, friction, and stiffness properties of the DMD elements were studied. The influence of relative humidity and temperature on the behavior of the DMD element surfaces was also investigated. Potential mechanisms for wear and stiction are discussed in light of the findings.

  14. Atomic force microscopy characterization of the surface wettability of natural fibres

    Science.gov (United States)

    Pietak, Alexis; Korte, Sandra; Tan, Emelyn; Downard, Alison; Staiger, Mark P.

    2007-01-01

    Natural fibres represent a readily available source of ecologically friendly and inexpensive reinforcement in composites with degradable thermoplastics, however chemical treatments of fibres are required to prepare feasible composites. It is desirable to characterize the surface wettability of fibres after chemical treatment as the polarity of cellulose-based fibres influences compatibility with a polymer matrix. Assessment of the surface wettability of natural fibres using conventional methods presents a challenge as the surfaces are morphologically and chemically heterogeneous, rough, and can be strongly wicking. In this work it is shown that under atmospheric conditions the adhesion force between an atomic force microscopy (AFM) tip and the fibre surface can estimate the water contact angle and surface wettability of the fibre. AFM adhesion force measurements are suitable for the more difficult surfaces of natural fibres and in addition allow for correlations between microstructural features and surface wettability characteristics.

  15. Characterization of single-crystal sapphire substrates by X-ray methods and atomic force microscopy

    International Nuclear Information System (INIS)

    The possibility of characterizing a number of practically important parameters of sapphire substrates by X-ray methods is substantiated. These parameters include wafer bending, traces of an incompletely removed damaged layer that formed as a result of mechanical treatment (scratches and marks), surface roughness, damaged layer thickness, and the specific features of the substrate real structure. The features of the real structure of single-crystal sapphire substrates were investigated by nondestructive methods of double-crystal X-ray diffraction and plane-wave X-ray topography. The surface relief of the substrates was investigated by atomic force microscopy and X-ray scattering. The use of supplementing analytical methods yields the most complete information about the structural inhomogeneities and state of crystal surface, which is extremely important for optimizing the technology of substrate preparation for epitaxy.

  16. Characterization of a thermoset-thermoplastic interphase using the atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, N.D.; Lesko, J.J.; Harris, L.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)] [and others

    1996-12-31

    Recent investigators have shown that the performance of polymer matrix composites can be significantly enhanced by using fibers sized with a thermoplastic polymer. This increase in performance is a result of the sizing material interacting with the matrix resin to form an interphase: a region possessing a gradient in properties different from the sizing material and the matrix resin. Although the influence of the sizing (interphase) on laminate properties has been well documented, quantitative information regarding interphase properties is absent. In this study, {open_quotes}model{close_quotes} composites consisting of polyurethane sized carbon fibers embedded in a vinyl ester matrix were fabricated to characterize the interphase. The atomic force microscope was used to identify the interphase region in these {open_quotes}model{close_quotes} composites.

  17. Morphology of Platinum Nanowire Array Electrodeposited Within Anodic Aluminium Oxide Template Characterized by Atomic Force Microscopy

    Institute of Scientific and Technical Information of China (English)

    孔令斌; 陆梅; 李梦轲; 郭新勇; 力虎林

    2003-01-01

    Uniform platinum nanowires were synthesized by electrodepositing the platinum under a very low altering current frequency (20Hz) and increasing voltage (5-15 V) in the pores of anodic aluminium oxide (AAO) template.Atomic force microscopy observation indicates that the template membranes we obtained have hexagonally closepacked nanochannels. The platinum nanowires have highly ordered arrays after partially dissolving the aluminium oxide membrane. With the increasing dissolving time, the platinum nanowire array collapsed. A concave topography of the aluminium substrate was observed after the aluminium oxide membrane was dissolved completely and the platinum nanowires were released from the template. Platinum nanowires were also characterized by transmission electron microscopy and the phase structure of the Al/AAO/Pt composite was proven by x-ray diffraction.

  18. Transmission electron microscopy and atomic force microscopy characterization of nickel deposition on bacterial cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Recently bacterial cells have become attractive biological templates for the fabrication of metal nano- structures or nanomaterials due to their inherent small size, various standard geometrical shapes and abundant source. In this paper, nickel-coated bacterial cells (gram-negative bacteria of Escherichia coli) were fabricated via electroless chemical plating. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) characterization results reveal evident morphological difference between bacterial cells before and after deposition with nickel. The bare cells with smooth surface presented transverse outspreading effect at mica surface. Great changes took place in surface roughness for those bacterial cells after metallization. A large number of nickel nanoparticles were observed to be equably distributed at bacterial surface after activation and subsequent metallization. Furthermore, ultra thin section analytic results validated the presence and uniformity of thin nickel coating at bacterial surface after metallization.

  19. Surface topography characterization using an atomic force microscope mounted on a coordinate measuring machine

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Hansen, H.N; Kofod, N

    1999-01-01

    The paper describes the construction, testing and use of an integrated system for topographic characterization of fine surfaces on parts having relatively big dimensions. An atomic force microscope (AFM) was mounted on a manual three-coordinate measuring machine (CMM) achieving free positioning...... values in the order of 1 nm. The positioning repeatability of the two horizontal axes of the CMM was determined to +/-1 mu m. Sets of four 20 mu m x 20 mu m areas were traced on fiat objects, combining the data into single 40 mu m x 40 mu m areas, and comparing the roughness values to those for the same...... areas traced in single scans of 40 mu m x 40 mu m. The results show that surface mapping on industrial surfaces is possible using the Least Mean Square alignment provided by the AFM software....

  20. Battery-Free Love-Wave-Based Neural Probe and Its Wireless Characterizations

    Science.gov (United States)

    Jung, In Ki; Fu, Chen; Lee, Keekeun

    2013-06-01

    A wireless Love-wave-based neural probe that utilizes a one-port reflective delay line was developed for both reading and stimulating neurons in the brain. Poly(methyl methacrylate) (PMMA) as a waveguide layer and gold (Au) electrodes were structured on the top of a 41° YX LiNbO3 piezoelectric substrate, following the parameters extracted from coupling-of-mode (COM) modeling. For a one-port reflective delay line, single-phase unidirectional transducers (SPUDTs) and three shorted grating reflectors were employed, which made possible the implementation of a wireless and battery-free neural probe. The fabricated Love-wave-based neural probes were wirelessly measured using two antennas with a 440 MHz central frequency and a network analyzer. Sharp reflection peaks with a high signal-to-noise ratio were observed from the reflection peaks. The probe was immersed in 0.9% saline solution while applying input DC voltages. Good linearity, high sensitivity, and reproducibility were observed depending on DC applied voltage, in the range from 0 to 500 mV. The sensitivity obtained from the DC firings (artificial neural firings) was ˜0.04 µs/VDC, indicating that this prototype probe is very promising for the wireless reading and stimulation of neural firings in in vivo animal testing.

  1. Influence of long-term thermal aging on the microstructural evolution of nuclear reactor pressure vessel materials: An atom probe study

    Energy Technology Data Exchange (ETDEWEB)

    Pareige, P.; Russell, K.F.; Stoller, R.E.; Miller, M.K. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Atom probe field ion microscopy (APFIM) investigations of the microstructure of unaged (as-fabricated) and long-term thermally aged ({approximately} 100,000 h at 280 C) surveillance materials from commercial reactor pressure vessel steels were performed. This combination of materials and conditions permitted the investigation of potential thermal-aging effects. This microstructural study focused on the quantification of the compositions of the matrix and carbides. The APFIM results indicate that there was no significant microstructural evolution after a long-term thermal exposure in weld, plate, or forging materials. The matrix depletion of copper that was observed in weld materials was consistent with the copper concentration in the matrix after the stress-relief heat treatment. The compositions of cementite carbides aged for 100,000 h were compared with the Thermocalc{trademark} prediction. The APFIM comparisons of materials under these conditions are consistent with the measured change in mechanical properties such as the Charpy transition temperature.

  2. Mechanism of Origin and Neutralization of Residual Triboelectricity at Scanning of Dielectric Surfaces by a Silicon Probe of the Atomic-force Microscope

    Directory of Open Access Journals (Sweden)

    М.А. Bondarenko

    2014-06-01

    Full Text Available The reasons and mechanism of the destructive effect of the electrostatic interaction forces of silicon probe and dielectric surfaces are established in the paper at the investigation of the surface microgeometry and mechanical characteristics by the atomic-force microscopy method. Calculation of the electrostatic interaction forces of two silicon surfaces is carried out and the destructive effect of electrostatic discharge appearing as a result of triboelectric effect is determined. The module of removal of electrostatic charge is proposed. Its principle of operation consists in the formation of the conduction band in the place of contact of two dielectrics by the multiphoton ionization. It is shown that application of such method of neutralization of residual triboelectricity improves accuracy, reliability, and reproducibility of the scanning results.

  3. Laser-induced reversion of $\\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    CERN Document Server

    Khushaim, Muna; Al-Kassab, Talaat

    2015-01-01

    The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser energy of 100 pJ was in fairly good agreement with reported range of $\\delta^{'}$ solvus temperature, suggesting a result of reversion upon heating due to laser pulsing.

  4. Atom Probe Tomography Study of Multi-microalloyed Carbide and Carbo-Nitride Precipitates and the Precipitation Sequence in Nb-Ti HSLA Steels

    Science.gov (United States)

    Kapoor, Monica; O'Malley, Ronald; Thompson, Gregory B.

    2016-05-01

    Composition analysis of carbide and carbo-nitride precipitates was performed for two Nb-Ti microalloyed steels with yield strengths of 750 and 580 MPa using an atom probe study. In the high-Ti 750 MPa steel, Ti-rich (Ti,Nb)(C,N) and Ti-rich (Ti,Nb)(C) precipitates were observed. In the high-Nb 580 MPa steel, a Ti-rich (Ti,Nb)(C,N) precipitate and (Ti,Nb)(C) clusters were noted. These (Ti,Nb)(C) clusters in the high-Nb 580 MPa steel were smaller than the (Ti,Nb)(C) precipitates in high-Ti 750 MPa steel. In general, a larger number of precipitates were found in the high-Ti 750 MPa steel. This difference in the number density of the precipitates between the two steels is attributed to the difference in Ti content. Combining the atom probe tomography results and thermodynamic calculations, the precipitation sequence in these alloys was inferred to be the following: as the temperature decreases, TiN precipitates out of the solution with successive (Ti,Nb)(C,N) layers of varying composition forming on these Ti-rich precipitates. Once N is depleted from the solution, a second set of (Ti,Nb)(C) precipitates in a similar manner in the matrix and also onto the carbo-nitride phase. This observation is consistent with previous observations in high-strength low-alloy steels containing comparable amounts of only Nb. It was noted that the amount of Nb, Nb/(Nb + Ti), in the precipitates decreased from 0.20 to 0.04 with the size of the precipitate. We believe that this is due to the Nb supersaturation in the matrix when these precipitates nucleate.

  5. Probing the elastic response of microalga Scenedesmus dimorphus in dry and aqueous environments through atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Warren, K. M.; Mpagazehe, J. N.; Higgs, C. F., E-mail: prl@andrew.cmu.edu, E-mail: higgs@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); LeDuc, P. R., E-mail: prl@andrew.cmu.edu, E-mail: higgs@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); Departments of Biomedical Engineering and Biological Sciences, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213 (United States)

    2014-10-20

    With the re-emergence of microalgae as a replacement feedstock for petroleum-derived oils, researchers are working to understand its chemical and mechanical behavior. In this work, the mechanical properties of microalgae, Scenedesmus dimorphus, were investigated at the subcellular level to determine the elastic response of cells that were in an aqueous and dried state using nano-scale indentation through atomic force microscopy. The elastic modulus of single-celled S. dimorphus cells increased over tenfold from an aqueous state to a dried state, which allows us to better understand the biophysical response of microalgae to stress.

  6. Attosecond time delay in the photoionization of endohedral atoms A@C$_{60}$: A new probe of confinement resonances

    CERN Document Server

    Deshmukh, P C; Saha, S; Kheifets, A S; Dolmatov, V K; Manson, S T

    2014-01-01

    The effects of confinement resonances on photoelectron group delay (Wigner time delay) following ionization of an atom encapsulated inside a C$_{60}$ cage have been studied theoretically using both relativistic and non-relativistic random phase approximations. The results indicate clearly the resonant character of the confinement oscillations in time delay of the $4d$ shell of Xe@C$_{60}$ and present a most direct manifestation of Wigner time delay. These oscillations were missed in a previous theoretical investigation of Ar@C$_{60}$ [PRL 111, 203003 (2013)

  7. Quantifying adhesion of acidophilic bioleaching bacteria to silica and pyrite by atomic force microscopy with a bacterial probe.

    Science.gov (United States)

    Diao, Mengxue; Taran, Elena; Mahler, Stephen; Nguyen, Tuan A H; Nguyen, Anh V

    2014-03-01

    The adhesion of acidophilic bacteria to mineral surfaces is an important phenomenon in bioleaching processes. In this study, functionalized colloidal probes covered by bioleaching bacterial cells (Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans) were developed and used to sense specific adhesion forces to a silica surface and a pyrite surface in various solutions. Experimentally, recorded retraction curves of A. thiooxidans revealed sawtooth features that were in good agreement with the wormlike chain model, while that of L. ferrooxidans exhibited stair-step separation. The magnitudes of adhesion forces and snap-off distances were strongly influenced by the ionic strength and pH. Macroscopic surface properties including hydrophobicity and surface potential for bacterial cells and substrata were measured by a sessile drop method and microelectrophoresis. The ATR-FTIR spectra indicated the presence of different types of biopolymers on two strains of bacteria.

  8. Characterizing entanglement of an artificial atom and a cavity cat state with Bell's inequality.

    Science.gov (United States)

    Vlastakis, Brian; Petrenko, Andrei; Ofek, Nissim; Sun, Luyan; Leghtas, Zaki; Sliwa, Katrina; Liu, Yehan; Hatridge, Michael; Blumoff, Jacob; Frunzio, Luigi; Mirrahimi, Mazyar; Jiang, Liang; Devoret, M H; Schoelkopf, R J

    2015-01-01

    The Schrodinger's cat thought experiment highlights the counterintuitive concept of entanglement in macroscopically distinguishable systems. The hallmark of entanglement is the detection of strong correlations between systems, most starkly demonstrated by the violation of a Bell inequality. No violation of a Bell inequality has been observed for a system entangled with a superposition of coherent states, known as a cat state. Here we use the Clauser-Horne-Shimony-Holt formulation of a Bell test to characterize entanglement between an artificial atom and a cat state, or a Bell-cat. Using superconducting circuits with high-fidelity measurements and real-time feedback, we detect correlations that surpass the classical maximum of the Bell inequality. We investigate the influence of decoherence with states up to 16 photons in size and characterize the system by introducing joint Wigner tomography. Such techniques demonstrate that information stored in superpositions of coherent states can be extracted efficiently, a crucial requirement for quantum computing with resonators. PMID:26611724

  9. Transformation twinning of Ni-Mn-Ga characterized with temperature-controlled atomic force microscopy.

    Science.gov (United States)

    Reinhold, Matthew; Watson, Chad; Knowlton, William B; Müllner, Peter

    2010-06-01

    The magnetomechanical properties of ferromagnetic shape memory alloy Ni-Mn-Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni-Mn-Ga single crystal. Experiments were performed in the martensite phase at 25 degrees C and in the austenite phase at 55 degrees C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature (55 degrees C), the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25 degrees C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys.

  10. Characterization of Predominant Reductants in an Anaerobic Leachate-Contaminated Aquifer by Nitroaromatic Probe Compounds

    DEFF Research Database (Denmark)

    Rügge, Kirsten; Hofstetter, Thomas B.; Haderlein, Stefan B.;

    1998-01-01

    The biogeochemical processes controlling the reductive transformation of contaminants in an anaerobic aquifer were inferred from the relative reactivity patterns of redox-sensitive probe compounds. The fate of five nitroaromatic compounds (NACs) was monitored under different redox conditions in a...

  11. Dopant Diffusion and Activation in Silicon Nanowires Fabricated by ex Situ Doping: A Correlative Study via Atom-Probe Tomography and Scanning Tunneling Spectroscopy.

    Science.gov (United States)

    Sun, Zhiyuan; Hazut, Ori; Huang, Bo-Chao; Chiu, Ya-Ping; Chang, Chia-Seng; Yerushalmi, Roie; Lauhon, Lincoln J; Seidman, David N

    2016-07-13

    Dopants play a critical role in modulating the electric properties of semiconducting materials, ranging from bulk to nanoscale semiconductors, nanowires, and quantum dots. The application of traditional doping methods developed for bulk materials involves additional considerations for nanoscale semiconductors because of the influence of surfaces and stochastic fluctuations, which may become significant at the nanometer-scale level. Monolayer doping is an ex situ doping method that permits the post growth doping of nanowires. Herein, using atom-probe tomography (APT) with subnanometer spatial resolution and atomic-ppm detection limit, we study the distributions of boron and phosphorus in ex situ doped silicon nanowires with accurate control. A highly phosphorus doped outer region and a uniformly boron doped interior are observed, which are not predicted by criteria based on bulk silicon. These phenomena are explained by fast interfacial diffusion of phosphorus and enhanced bulk diffusion of boron, respectively. The APT results are compared with scanning tunneling spectroscopy data, which yields information concerning the electrically active dopants. Overall, comparing the information obtained by the two methods permits us to evaluate the diffusivities of each different dopant type at the nanowire oxide, interface, and core regions. The combined data sets permit us to evaluate the electrical activation and compensation of the dopants in different regions of the nanowires and understand the details that lead to the sharp p-i-n junctions formed across the nanowire for the ex situ doping process.

  12. Post-irradiation annealing of Ni–Mn–Si-enriched clusters in a neutron-irradiated RPV steel weld using Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Styman, P.D., E-mail: paul.styman@materials.ox.ac.uk [National Nuclear Laboratory, 168 Harwell Business Centre, Didcot, Oxon OX11 0QT (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Hyde, J.M. [National Nuclear Laboratory, 168 Harwell Business Centre, Didcot, Oxon OX11 0QT (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Parfitt, D.; Wilford, K. [Rolls-Royce, PO BOX 2000, Raynesway, Derby DE21 7XX (United Kingdom); Burke, M.G. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); English, C.A. [National Nuclear Laboratory, 168 Harwell Business Centre, Didcot, Oxon OX11 0QT (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Efsing, P. [Vattenfall Ringhals AB, Väröbacka (Sweden)

    2015-04-15

    Highlights: • Characterisation of high Ni neutron irradiated RPV surveillance samples at high fluence. • Post-irradiation annealing performed to give insight into the formation mechanisms of Ni–Mn–Si precipitates. • Dissolution of Ni–Mn–Si clusters appears to be lead by the removal of Mn. - Abstract: Atom Probe Tomography has been performed on as-irradiated and post-irradiation annealed surveillance weld samples from Ringhals Unit 3. The weld contains low Cu (0.07 at.%) and high Ni (1.5 at.%). A high number density (∼4 × 10{sup 23} m{sup −3}) of Ni–Mn–Si-enriched clusters was observed in the as-irradiated material. The onset of recovery was observed during the annealing for 30 min at 450 °C. Much more significant dissolution of clusters occurred during the 10 min 500 °C anneal, resulting in a reduction in mean cluster size and a halving of their volume fraction. Detailed analyses of the changes in microstructure demonstrate that the dissolution process is driven by migration of Mn atoms from the clusters. This may indicate a strong correlation between Mn and point defects. Dissolution of the clusters is shown to correlate with recovery of mechanical properties in this material.

  13. Atom probe tomography study of internal interfaces in Cu{sub 2}ZnSnSe{sub 4} thin-films

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, T., E-mail: schwarz@mpie.de; Cojocaru-Mirédin, O.; Choi, P., E-mail: choi@mpie.de; Raabe, D. [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf (Germany); Mousel, M.; Redinger, A.; Siebentritt, S. [Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, L-4422 Belvaux (Luxembourg)

    2015-09-07

    We report on atom probe tomography studies of the composition at internal interfaces in Cu{sub 2}ZnSnSe{sub 4} thin-films. For Cu{sub 2}ZnSnSe{sub 4} precursors, which are deposited at 320 °C under Zn-rich conditions, grain boundaries are found to be enriched with Cu irrespective of whether Cu-poor or Cu-rich growth conditions are chosen. Cu{sub 2}ZnSnSe{sub 4} grains are found to be Cu-poor and excess Cu atoms are found to be accumulated at grain boundaries. In addition, nanometer-sized ZnSe grains are detected at or near grain boundaries. The compositions at grain boundaries show different trends after annealing at 500 °C. Grain boundaries in the annealed absorber films, which are free of impurities, are Cu-, Sn-, and Se-depleted and Zn-enriched. This is attributed to dissolution of ZnSe at the Cu-enriched grain boundaries during annealing. Furthermore, some of the grain boundaries of the absorbers are enriched with Na and K atoms, stemming from the soda-lime glass substrate. Such grain boundaries show no or only small changes in composition of the matrix elements. Na and K impurities are also partly segregated at some of the Cu{sub 2}ZnSnSe{sub 4}/ZnSe interfaces in the absorber, whereas for the precursors, only Na was detected at such phase boundaries possibly due to a higher diffusivity of Na compared to K. Possible effects of the detected compositional fluctuations on cell performance are discussed.

  14. Note: A silicon-on-insulator microelectromechanical systems probe scanner for on-chip atomic force microscopy.

    Science.gov (United States)

    Fowler, Anthony G; Maroufi, Mohammad; Moheimani, S O Reza

    2015-04-01

    A new microelectromechanical systems-based 2-degree-of-freedom (DoF) scanner with an integrated cantilever for on-chip atomic force microscopy (AFM) is presented. The silicon cantilever features a layer of piezoelectric material to facilitate its use for tapping mode AFM and enable simultaneous deflection sensing. Electrostatic actuators and electrothermal sensors are used to accurately position the cantilever within the x-y plane. Experimental testing shows that the cantilever is able to be scanned over a 10 μm × 10 μm window and that the cantilever achieves a peak-to-peak deflection greater than 400 nm when excited at its resonance frequency of approximately 62 kHz.

  15. Detection of atomic spin labels in a lipid bi-layer using a single-spin nanodiamond probe

    CERN Document Server

    Kaufmann, Stefan; Hall, Liam T; Perunicic, Viktor; Senn, Philipp; Steinert, Steffen; McGuinness, Liam P; Johnson, Brett C; Ohshima, Takeshi; Caruso, Frank; Wrachtrup, Joerg; Scholten, Robert E; Mulvaney, Paul; Hollenberg, Lloyd C L

    2013-01-01

    Magnetic field fluctuations arising from fundamental spins are ubiquitous in nanoscale biology, and are a rich source of information about the processes that generate them. However, the ability to detect the few spins involved without averaging over large ensembles has remained elusive. Here we demonstrate the detection of gadolinium spin labels in an artificial cell membrane under ambient conditions using a single-spin nanodiamond sensor. Changes in the spin relaxation time of the sensor located in the lipid bilayer were optically detected and found to be sensitive to near-individual proximal gadolinium atomic labels. The detection of such small numbers of spins in a model biological setting, with projected detection times of one second, opens a new pathway for in-situ nanoscale detection of dynamical processes in biology.

  16. Note: A silicon-on-insulator microelectromechanical systems probe scanner for on-chip atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, Anthony G.; Maroufi, Mohammad; Moheimani, S. O. Reza, E-mail: Reza.Moheimani@newcastle.edu.au [School of Electrical Engineering and Computer Science, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2015-04-15

    A new microelectromechanical systems-based 2-degree-of-freedom (DoF) scanner with an integrated cantilever for on-chip atomic force microscopy (AFM) is presented. The silicon cantilever features a layer of piezoelectric material to facilitate its use for tapping mode AFM and enable simultaneous deflection sensing. Electrostatic actuators and electrothermal sensors are used to accurately position the cantilever within the x-y plane. Experimental testing shows that the cantilever is able to be scanned over a 10 μm × 10 μm window and that the cantilever achieves a peak-to-peak deflection greater than 400 nm when excited at its resonance frequency of approximately 62 kHz.

  17. Review of electrical characterization of ultra-shallow junctions with micro four-point probes

    DEFF Research Database (Denmark)

    Petersen, Dirch Hjorth; Hansen, Ole; Hansen, Torben M.;

    2010-01-01

    Electrical characterization of ultra-shallow junctions, relying on advanced implant and anneal processes, has received much attention in the past few years since conventional characterization methods fail. With continued scaling of semiconductor devices, the problems associated with conventional...

  18. A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization

    Science.gov (United States)

    Berger, Andrew J.; Page, Michael R.; Jacob, Jan; Young, Justin R.; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P.; Johnston-Halperin, Ezekiel; Pelekhov, Denis V.; Hammel, P. Chris

    2014-12-01

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.

  19. A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Andrew J., E-mail: berger.156@osu.edu; Page, Michael R.; Young, Justin R.; Bhallamudi, Vidya P.; Johnston-Halperin, Ezekiel; Pelekhov, Denis V.; Hammel, P. Chris [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Jacob, Jan [Werum Software and Systems CIS AG, Wulf-Werum-Straße 3, 21337 Lüneburg (Germany); Lewis, Jim; Wenzel, Lothar [National Instruments, Austin, Texas 78759 (United States)

    2014-12-15

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.

  20. A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization.

    Science.gov (United States)

    Berger, Andrew J; Page, Michael R; Jacob, Jan; Young, Justin R; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P; Johnston-Halperin, Ezekiel; Pelekhov, Denis V; Hammel, P Chris

    2014-12-01

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field. PMID:25554296

  1. A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization

    International Nuclear Information System (INIS)

    Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field

  2. Optical characterization of nanocrystalline boron nitride thin films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Snure, Michael, E-mail: michael.snure.1@us.af.mil [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States); Paduano, Qing; Hamilton, Merle [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States); Shoaf, Jodie [Wyle Laboratories, Inc., Wright-Patterson AFB, OH (United States); Mann, J. Matthew [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States)

    2014-11-28

    Boron nitride thin films were grown on sapphire and Si substrates by atomic layer deposition from triethylborane (TEB) and NH{sub 3} precursors in the temperature range of 500 to 900 °C. By varying the TEB exposure the film thickness can be controlled with< 1 nm precision. At 600 °C the process is self-limiting, but films are found to be amorphous. Films grown at higher temperatures were identified as sp{sup 2} BN, but the process is no longer self-limiting. From Raman and IR absorption spectroscopy films deposited at 900 °C were identified as nanocrystalline sp{sup 2} BN with crystallite sizes in the range of 3 to 8 nm depending on the NH{sub 3} dosage. Films deposited at lower temperatures had broad red shifted IR absorption peaks indicating the lack of long range ordering. The visible and UV optical properties of these films were characterized by UV–Vis transmission measurements over the range of 800 to 190 nm. Nanocrystalline films are highly transparent over this range up to the band gap, which was measured to be in the range of 5.83 to 5.65 eV depending on the NH{sub 3} dosage. - Highlights: • Atomic layer deposition of BN with< 1 nm per cycle deposition rates • A narrow self-limiting temperature window was found. • Nanocrystalline h-BN films with a wide transparence window with E{sub g} up to 5.85 eV.

  3. In-vivo characterization of DALM in ulcerative colitis with high-resolution probe-based confocal laser endomicroscopy

    Institute of Scientific and Technical Information of China (English)

    Giovanni D De Palma; Stefania Staibano; Saverio Siciliano; Francesco Maione; Maria Siano; Dario Esposito; Giovanni Persico; Yang Yi

    2011-01-01

    Recently, the use of confocal laser endomicroscopy (CLE)in the diagnosis of chronic ulcerative colitis (CUC) was reported. In this brief report we aimed to assess the application of probe-based CLE to characterize colonic mucosa and dysplasia in CUC. The study involved a patient presenting long-standing CUC. Confocal imaging of both the inflamed mucosa, a circumscribed lesion (dysplasiaassociated lesional mass), and adjacent colonic mucosa are demonstrated and the correlation between the CLE and histological images. Inflamed mucosa and dysplasia showed specific alteration of crypt architecture, cellular infiltration, and vessel architecture with an excellent correlation between CLE and standard histological examination.

  4. Characterization of post-copper CMP surfaces with scanning probe microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dominget, A. [Freescale Semiconductor, Crolles2 Alliance, 870 Rue Jean Monnet, 38926 Crolles (France); Farkas, J. [Freescale Semiconductor, Crolles2 Alliance, 870 Rue Jean Monnet, 38926 Crolles (France)]. E-mail: Janos.Farkas@freescale.com; Szunerits, S. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces (LEPMI), CNRS-INPG-UJF, 1130 Rue de la Piscine, BP 75, 38402 St. Martin d' Heres (France)]. E-mail: sabine.szunerits@lepmi.inpg.fr

    2006-09-15

    We demonstrate in this paper for the first time the use of conductive atomic force microscopy (AFM) to measure surface leakage between copper structures with varying line width and spacing in the micro and sub micrometer ranges. Conducting atomic force microscopy allows subsequent measurement of the topography as well as the electrical properties of surfaces. The feasibility and interest of these measurements will be shown by studying the impact of chemical mechanical polishing (CMP) of an electrical interface bearing different micrometric copper structures. As expected the polishing time has a crucial impact on the current determined between closely spaced copper structures. This paper will also deal with issues observed during the measurement.

  5. Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

    Energy Technology Data Exchange (ETDEWEB)

    Morawski, Ireneusz [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany); Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław (Poland); Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2015-12-15

    A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

  6. Probing the Structure and Chemistry of Perylenetetracarboxylic Dianhydride on Graphene Before and After Atomic Layer Deposition of Alumina.

    Science.gov (United States)

    Johns, James E; Karmel, Hunter J; Alaboson, Justice M P; Hersam, Mark C

    2012-07-11

    The superlative electronic properties of graphene suggest its use as the foundation of next generation integrated circuits. However, this application requires precise control of the interface between graphene and other materials, especially the metal oxides that are commonly used as gate dielectrics. Towards that end, organic seeding layers have been empirically shown to seed ultrathin dielectric growth on graphene via atomic layer deposition (ALD), although the underlying chemical mechanisms and structural details of the molecule/dielectric interface remain unknown. Here, confocal resonance Raman spectroscopy is employed to quantify the structure and chemistry of monolayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on graphene before and after deposition of alumina with the ALD precursors trimethyl aluminum (TMA) and water. Photoluminescence measurements provide further insight into the details of the growth mechanism, including the transition between layer-by-layer growth and island formation. Overall, these results reveal that PTCDA is not consumed during ALD, thereby preserving a well-defined and passivating organic interface between graphene and deposited dielectric thin films. PMID:22905282

  7. Experimental validation of a method characterizing bow tie filters in CT scanners using a real-time dose probe

    Energy Technology Data Exchange (ETDEWEB)

    McKenney, Sarah E.; Nosratieh, Anita; Gelskey, Dale; Yang Kai; Huang Shinying; Chen Lin; Boone, John M. [Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States) and Department of Biomedical Engineering, University of California, Davis, Rm. 2303, GBSF, 451 E. Health Science Dr., Davis, California 95616 (United States); Diagnostic Imaging Specialists Corporation (DISC), 163 St. Malo Street, St. Malo, Manitoba R0A 1T0 (Canada); Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States) and Department of Biomedical Engineering, University of California, Davis, Rm. 2303, GBSF, 451 E. Health Science Dr., Davis, California 95616 (United States)

    2011-03-15

    Purpose: Beam-shaping or ''bow tie'' (BT) filters are used to spatially modulate the x-ray beam in a CT scanner, but the conventional method of step-and-shoot measurement to characterize a beam's profile is tedious and time-consuming. The theory for characterization of bow tie relative attenuation (COBRA) method, which relies on a real-time dosimeter to address the issues of conventional measurement techniques, was previously demonstrated using computer simulations. In this study, the feasibility of the COBRA theory is further validated experimentally through the employment of a prototype real-time radiation meter and a known BT filter. Methods: The COBRA method consisted of four basic steps: (1) The probe was placed at the edge of a scanner's field of view; (2) a real-time signal train was collected as the scanner's gantry rotated with the x-ray beam on; (3) the signal train, without a BT filter, was modeled using peak values measured in the signal train of step 2; and (4) the relative attenuation of the BT filter was estimated from filtered and unfiltered data sets. The prototype probe was first verified to have an isotropic and linear response to incident x-rays. The COBRA method was then tested on a dedicated breast CT scanner with a custom-designed BT filter and compared to the conventional step-and-shoot characterization of the BT filter. Using basis decomposition of dual energy signal data, the thickness of the filter was estimated and compared to the BT filter's manufacturing specifications. The COBRA method was also demonstrated with a clinical whole body CT scanner using the body BT filter. The relative attenuation was calculated at four discrete x-ray tube potentials and used to estimate the thickness of the BT filter. Results: The prototype probe was found to have a linear and isotropic response to x-rays. The relative attenuation produced from the COBRA method fell within the error of the relative attenuation

  8. A comment on "the far future of exoplanet direct characterization"--the case for interstellar space probes.

    Science.gov (United States)

    Crawford, Ian A

    2010-10-01

    Following on from ideas presented in a recent paper by Schneider et al. on "The Far Future of Exoplanet Direct Characterization," I argue that they have exaggerated the technical obstacles to performing such "direct characterization" by means of fast (order 0.1c) interstellar space probes. A brief summary of rapid interstellar spaceflight concepts that may be found in the literature is presented. I argue that the presence of interstellar dust grains, while certainly something that will need to be allowed for in interstellar vehicle design, is unlikely to be the kind of showstopper suggested by Schneider et al. Astrobiology as a discipline would be a major beneficiary of developing an interstellar spaceflight capability, albeit in the longer term, and I argue that astrobiologists should keep an open mind to the possibilities.

  9. Novel four-point-probe design and nanorobotic dual endeffector strategy for electrical characterization of as-grown SWCNT bundles

    DEFF Research Database (Denmark)

    Eichhorn, V; Fatikow, S; Sardan Sukas, Özlem;

    2010-01-01

    In this paper, a novel nanorobotic strategy for non-destructive and direct electrical characterization of as-grown bundles of single-walled carbon nanotubes (SWCNTs) is presented. For this purpose, test patterns of SWCNT bundles having different diameters are grown on a silicon substrate by chemi......In this paper, a novel nanorobotic strategy for non-destructive and direct electrical characterization of as-grown bundles of single-walled carbon nanotubes (SWCNTs) is presented. For this purpose, test patterns of SWCNT bundles having different diameters are grown on a silicon substrate...... by chemical vapor deposition. A new design of microstructured four-point-probes is proposed and fabricated allowing for direct contacting of vertically aligned bundles of SWCNTs. A nanorobotic setup is upgraded into a dual endeffector system to achieve good electrical contact between four...

  10. Investigations of superconducting and non-superconducting YBa/sub 2/Cu/sub 3/0/sub 7-x/ by field ion microscopy, atom-probe mass spectroscopy and field electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, G.L.; Brenner, S.S.

    1988-11-01

    The structure and composition of superconducting and non-superconducting samples of YBa Cu 0 were examined by field ion microscopy, atom-probe mass spectroscopy and field-electron emission techniques. Field ion microscope images from both types of material exhibited ring structures associated with atomic or multiatomic layers and uniform, layer-by-layer field evaporation was possible. Atom-probe mass spectra contained signals corresponding to atomic and molecular oxygen, all three metals, and oxides of Cu and Y. Atom-probe mass spectra from the superconducting sample (x /similar to/ 0.35) contained a much larger molecular oxygen signal than mass spectra from the non-superconducting samples (x/similar to/O.8) indicating that oxygen in the Cu0 chains is field desorbed preferentially as molecular oxygen ions. Field electron emission from the superconducting samples exhibited normal Fowler-Nordheim characteristics above and below the superconducting transition temperature. Surface contaminates were found to decrease the work function of the material by as much as 39%.

  11. Finite element simulation for the mechanical characterization of soft biological materials by atomic force microscopy.

    Science.gov (United States)

    Valero, C; Navarro, B; Navajas, D; García-Aznar, J M

    2016-09-01

    The characterization of the mechanical properties of soft materials has been traditionally performed through uniaxial tensile tests. Nevertheless, this method cannot be applied to certain extremely soft materials, such as biological tissues or cells that cannot be properly subjected to these tests. Alternative non-destructive tests have been designed in recent years to determine the mechanical properties of soft biological tissues. One of these techniques is based on the use of atomic force microscopy (AFM) to perform nanoindentation tests. In this work, we investigated the mechanical response of soft biological materials to nanoindentation with spherical indenters using finite element simulations. We studied the responses of three different material constitutive laws (elastic, isotropic hyperelastic and anisotropic hyperelastic) under the same process and analyzed the differences thereof. Whereas linear elastic and isotropic hyperelastic materials can be studied using an axisymmetric simplification, anisotropic hyperelastic materials require three-dimensional analyses. Moreover, we established the limiting sample size required to determine the mechanical properties of soft materials while avoiding boundary effects. Finally, we compared the results obtained by simulation with an estimate obtained from Hertz theory. Hertz theory does not distinguish between the different material constitutive laws, and thus, we proposed corrections to improve the quantitative measurement of specific material properties by nanoindentation experiments.

  12. Spectroscopic characterization of ZrO2 thin films grown by atomic layer deposition

    International Nuclear Information System (INIS)

    Zirconium dioxide films grown by atomic layer deposition from ZrCl4 and H2O at substrate temperatures of 500-870 K were characterized using spectroscopic methods. A significant influence of the phase composition on absorption and photoluminescence spectra was observed. The band-gap energies determined from absorption spectra of films with monoclinic structure grown at 670-870 K ranged from 5.25 to 5.28 eV. Low-temperature (10 K) photoexcitation of these films resulted in a non-elementary emission band with the maximum at 4.25-4.35 eV, tentatively assigned to the radiative decay of self-trapped excitons. The low-energy edges of the excitation spectra coincided with the edges of intrinsic absorption. A film that was grown at 500 K and contained tetragonal ZrO2 with large amounts of impurities had an absorption edge at 5.26 eV and wide emission band at 3.0 eV, which could be excited at as low photon energy as 4.9 eV. (author)

  13. A New Method for Characterization of Natural Zeolites and Organic Nanostructure Using Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Domenico Fuoco

    2012-03-01

    Full Text Available In order to study and develop an economical solution to environmental pollution in water, a wide variety of materials have been investigated. Natural zeolites emerge from that research as the best in class of this category. Zeolites are natural materials which are relatively abundant and non biodegradable, economical and serve to perform processes of environmental remediation. This paper contains a full description of a new method to characterize the superficial properties of natural zeolites of exotic provenience (Caribbean Islets with atomic force microscopy (AFM. AFM works with the simplicity of the optical microscope and the high resolution typical of a transmission electron microscope (TEM. If the sample is conductive, structural information of mesoporous material is obtained using scanning and transmission electron microscopy (SEM and TEM, otherwise the sample has to be processed through the grafitation technique, but this procedure induces errors of topography. Therefore, the existing AFM method, to observe zeolite powders, is made in a liquid cell-head scanner. This work confirms that it is possible to use an ambient air-head scanner to obtain a new kind of microtopography. Once optimized, this new method will allow investigation of organic micelles, a very soft nanostructure of cetyltriammonium bromide (CTAB, upon an inorganic surface such as natural zeolites. The data also demonstrated some correlation between SEM microphotographies and AFM 3D images.

  14. Finite element simulation for the mechanical characterization of soft biological materials by atomic force microscopy.

    Science.gov (United States)

    Valero, C; Navarro, B; Navajas, D; García-Aznar, J M

    2016-09-01

    The characterization of the mechanical properties of soft materials has been traditionally performed through uniaxial tensile tests. Nevertheless, this method cannot be applied to certain extremely soft materials, such as biological tissues or cells that cannot be properly subjected to these tests. Alternative non-destructive tests have been designed in recent years to determine the mechanical properties of soft biological tissues. One of these techniques is based on the use of atomic force microscopy (AFM) to perform nanoindentation tests. In this work, we investigated the mechanical response of soft biological materials to nanoindentation with spherical indenters using finite element simulations. We studied the responses of three different material constitutive laws (elastic, isotropic hyperelastic and anisotropic hyperelastic) under the same process and analyzed the differences thereof. Whereas linear elastic and isotropic hyperelastic materials can be studied using an axisymmetric simplification, anisotropic hyperelastic materials require three-dimensional analyses. Moreover, we established the limiting sample size required to determine the mechanical properties of soft materials while avoiding boundary effects. Finally, we compared the results obtained by simulation with an estimate obtained from Hertz theory. Hertz theory does not distinguish between the different material constitutive laws, and thus, we proposed corrections to improve the quantitative measurement of specific material properties by nanoindentation experiments. PMID:27214690

  15. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, M. L.; Fnidiki, A., E-mail: abdeslem.fnidiki@univ-rouen.fr; Lardé, R.; Cuvilly, F.; Blum, I. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Lechevallier, L. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Département de GEII, Université de Cergy-Pontoise, rue d' Eragny, Neuville sur Oise, 95031 Cergy-Pontoise (France); Debelle, A.; Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, Bât. 108, 91405 Orsay (France); Viret, M. [Service de Physique de l' Etat Condensé (DSM/IRAMIS/SPEC), UMR 3680 CNRS, Bât. 772, Orme des Merisiers, CEA Saclay 91191 Gif sur Yvette (France); Marteau, M.; Eyidi, D.; Declémy, A. [Institut PPRIME, UPR 3346 CNRS, Université de Poitiers, ENSMA, SP2MI, téléport 2, 11 Bvd M. et P. Curie 86962 Futuroscope, Chasseneuil (France)

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  16. Distribution of Cold (≲300 K) Atomic Gas in Galaxies: Results from the GBT H i Absorption Survey Probing the Inner Halos (ρ < 20 kpc) of Low-z Galaxies

    Science.gov (United States)

    Borthakur, Sanchayeeta

    2016-10-01

    We present the Green Bank Telescope absorption survey of cold atomic hydrogen (≲300 K) in the inner halo of low-redshift galaxies. The survey aims to characterize the cold gas distribution and to address where the condensation—the process where ionized gas accreted by galaxies condenses into cold gas within the disks of galaxies—occurs. Our sample consists of 16 galaxy–quasar pairs with impact parameters of ≤20 kpc. We detected an H i absorber associated with J0958+3222 (NGC 3067) and H i emission from six galaxies. We also found two Ca ii absorption systems in the archival SDSS data associated with galaxies J0958+3222 and J1228+3706. Our detection rate of H i absorbers with optical depths of ≥0.06 is ∼7%. We also find that the cold H i phase (≲300 K) is 44(±18)% of the total atomic gas in the sightline probing J0958+3222. We find no correlation between the peak optical depth and impact parameter or stellar and H i radii normalized impact parameters, ρ/R 90 and ρ/R H i . We conclude that the process of condensation of inflowing gas into cold (≲300 K) H i occurs at the ρ ≪ 20 kpc. However, the warmer phase of neutral gas (T ∼ 1000 K) can exist out to much larger distances, as seen in emission maps. Therefore, the process of condensation of warm to cold H i is likely occurring in stages from ionized to warm H i in the inner halo and then to cold H i very close to the galaxy disk. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  17. Advanced characterization of carrier profiles in germanium using micro-machined contact probes

    DEFF Research Database (Denmark)

    Clarysse, T.; Konttinen, M.; Parmentier, B.;

    2012-01-01

    The accurate determination of the sheet resistance and carrier depth profile, i.e. active dopant profile, of shallow junction isolated structures involving new high mobility materials, such as germanium, is a crucial topic for future CMOS development. In this work, we discuss the capabilities of...... use of only two probes, a spreading resistance like setup is obtained with small spacing and drastically reduced electrical contact radii (~10 nm) leading to a substantial reduction of the correction factors which are normally required for converting spreading resistance profiles. We demonstrate the...

  18. Effects of post-irradiation annealing and re-irradiation on microstructure in surveillance test specimens of the Loviisa-1 reactor studied by atom probe tomography and positron annihilation

    Science.gov (United States)

    Toyama, T.; Kuramoto, A.; Nagai, Y.; Inoue, K.; Nozawa, Y.; Shimizu, Y.; Matsukawa, Y.; Hasegawa, M.; Valo, M.

    2014-06-01

    This paper presents a microstructural study of a surveillance test specimen from the Loviisa-1 reactor in Finland, which is a Russian-type pressurized water reactor (VVER-440), after initial irradiation to a neutron fluence of 2.5 × 1019 n/cm2 (E > 1 MeV), post-irradiation annealing at 475 °C for 100 h and re-irradiation to three different fluences up to 2.7 × 1019 n/cm2. Atom probe tomography (APT) and positron annihilation spectroscopy (PAS) were used to characterize the test specimens. APT results showed the formation of Cu-rich solute clusters (SCs) during the initial irradiation and their subsequent coarsening during annealing. After re-irradiation, a small number of SCs formed once again. The hardening due to the SCs was estimated using the Russell-Brown model based on the APT results, and was in good agreement with the measured hardening after the initial irradiation and post-irradiation annealing. In contrast, during the first-step of re-irradiation, the estimated hardening due to the SCs was smaller than the measured hardening. This suggested that the hardening after re-irradiation was due to some microstructure other than the observed SCs. This difference was attributed to newly-formed matrix defects during re-irradiation, which was supported by the PAS results. However in subsequent steps of re-irradiation, the hardening was almost constant.

  19. Characterization of individual molecular adsorption geometries by atomic force microscopy: Cu-TCPP on rutile TiO{sub 2} (110)

    Energy Technology Data Exchange (ETDEWEB)

    Jöhr, Res; Hinaut, Antoine; Pawlak, Rémy; Saha, Santanu; Goedecker, Stefan; Meyer, Ernst, E-mail: ernst.meyer@unibas.ch; Glatzel, Thilo [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Sadeghi, Ali [Physics Department, Shahid Beheshti University, G. C., Evin, 19839 Tehran (Iran, Islamic Republic of); Such, Bartosz; Szymonski, Marek [Department of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow (Poland)

    2015-09-07

    Functionalized materials consisting of inorganic substrates with organic adsorbates play an increasing role in emerging technologies like molecular electronics or hybrid photovoltaics. For such applications, the adsorption geometry of the molecules under operating conditions, e.g., ambient temperature, is crucial because it influences the electronic properties of the interface, which in turn determine the device performance. So far detailed experimental characterization of adsorbates at room temperature has mainly been done using a combination of complementary methods like photoelectron spectroscopy together with scanning tunneling microscopy. However, this approach is limited to ensembles of adsorbates. In this paper, we show that the characterization of individual molecules at room temperature, comprising the determination of the adsorption configuration and the electrostatic interaction with the surface, can be achieved experimentally by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We demonstrate this by identifying two different adsorption configurations of isolated copper(II) meso-tetra (4-carboxyphenyl) porphyrin (Cu-TCPP) on rutile TiO{sub 2} (110) in ultra-high vacuum. The local contact potential difference measured by KPFM indicates an interfacial dipole due to electron transfer from the Cu-TCPP to the TiO{sub 2}. The experimental results are verified by state-of-the-art first principles calculations. We note that the improvement of the AFM resolution, achieved in this work, is crucial for such accurate calculations. Therefore, high resolution AFM at room temperature is promising for significantly promoting the understanding of molecular adsorption.

  20. Study and realization of probes and nondestructive characterization by Eddy Current Testing of cementing steels layers

    International Nuclear Information System (INIS)

    The electromagnetic properties of steels depend on their composition, their micro-structures and constraints applied. It is therefore natural to try to use magnetic and electrical parameters of steels to evaluate their microstructure. The sensitivity to defects and other parameters of control can be improved by the optimal choice of the probe. It appears, after study of the different types of probes (ferritic, sweet steel, insulator) with different geometry (dish, conical,...), necessary to underline that the success of a research of feasibility depends largely on the good definition of measure collectors, such sort that they are adapted to the considered problem. A software has been elaborated, allowing to automate this control and to reconstitute images having two and three dimensions of the controlled samples. The realized experimentations have shown large possibilities of analysis by the Eddy current method, the evolution of the various metallurgic characteristics. They allow, besides the verification of the coating and the determination of its thickness, to give an overview on the percentage of the main chemical components of the controlled samples coating by a deepened processing. (Author)

  1. Scanning probe microscopies for the creation and characterization of interfacial architectures: Studies of alkyl thiolate monolayers at gold

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.

    1997-01-10

    Scanning probe microscopy (SPM) offers access to the structural and material properties of interfaces, and when combined with macroscopic characterization techniques results in a powerful interfacial development tool. However, the relative infancy of SPM techniques has dictated that initial investigations concentrate on model interfacial systems as benchmarks for testing the control and characterization capabilities of SPM. One such family of model interfacial systems results from the spontaneous adsorption of alkyl thiols to gold. This dissertation examines the application of SPM to the investigation of the interfacial properties of these alkyl thiolate monolayers. Structural investigations result in a proposed explanation for counterintuitive correlations between substrate roughness and heterogeneous electron transfer barrier properties. Frictional measurements are used for characterization of the surface free energy of a series of end-group functionalized monolayers, as well as for the material properties of monolayers composed of varying chain length alkyl thiols. Additional investigations used these characterization techniques to monitor the real-time evolution of chemical and electrochemical surface reactions. The results of these investigations demonstrates the value of SPM technology to the compositional mapping of surfaces, elucidation of interfacial defects, creation of molecularly sized chemically heterogeneous architectures, as well as to the monitoring of surface reactions. However, it is the future which will demonstrate the usefulness of SPM technology to the advancement of science and technology.

  2. Model-independent measurement of the charge density distribution along an Fe atom probe needle using off-axis electron holography without mean inner potential effects

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, V., E-mail: v.migunov@fz-juelich.de; Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); London, A. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Farle, M. [Fakultät für Physik and Center of Nanointegration (CeNIDE), Universität Duisburg-Essen, D-47048 Duisburg (Germany)

    2015-04-07

    The one-dimensional charge density distribution along an electrically biased Fe atom probe needle is measured using a model-independent approach based on off-axis electron holography in the transmission electron microscope. Both the mean inner potential and the magnetic contribution to the phase shift are subtracted by taking differences between electron-optical phase images recorded with different voltages applied to the needle. The measured one-dimensional charge density distribution along the needle is compared with a similar result obtained using model-based fitting of the phase shift surrounding the needle. On the assumption of cylindrical symmetry, it is then used to infer the three-dimensional electric field and electrostatic potential around the needle with ∼10 nm spatial resolution, without needing to consider either the influence of the perturbed reference wave or the extension of the projected potential outside the field of view of the electron hologram. The present study illustrates how a model-independent approach can be used to measure local variations in charge density in a material using electron holography in the presence of additional contributions to the phase, such as those arising from changes in mean inner potential and specimen thickness.

  3. Study on microstructural changes in thermally-aged stainless steel weld-overlay cladding of nuclear reactor pressure vessels by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, T., E-mail: takeuchi.tomoaki@jaea.go.jp [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kameda, J. [National Institute for Materials Science, Sengen, Tsukuba 305-0047 (Japan); Nagai, Y.; Toyama, T. [Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nishiyama, Y.; Onizawa, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2011-08-15

    Highlights: > Microstructural changes in stainless steel electroslag weld-overlay cladding. > Thermal aging caused progress of spinodal decomposition and precipitation of G phases in the {delta}-ferrite phase. > The degree of the spinodal decomposition had a linear relationship to the hardness. - Abstract: The effect of thermal aging on microstructural changes was investigated in stainless steel weld-overlay cladding composed of 90% austenite and 10% {delta}-ferrite phases using atom probe tomography (APT). In as-received materials subjected to cooling process after post-welding heat treatments (PWHT), a slight fluctuation of the Cr concentration was already observed due to spinodal decomposition in the ferrite phase but not in the austenitic phase. Thermal aging at 400 deg. C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the ferrite phase. The chemical compositions of M{sub 23}C{sub 6} type carbides seemed to be formed at the austenite/ferrite interface were analyzed. The analyses of the magnitude of the spinodal decomposition and the hardness implied that the spinodal decomposition was the main cause of the hardening.

  4. Study on microstructural changes in thermally-aged stainless steel weld-overlay cladding of nuclear reactor pressure vessels by atom probe tomography

    International Nuclear Information System (INIS)

    Highlights: → Microstructural changes in stainless steel electroslag weld-overlay cladding. → Thermal aging caused progress of spinodal decomposition and precipitation of G phases in the δ-ferrite phase. → The degree of the spinodal decomposition had a linear relationship to the hardness. - Abstract: The effect of thermal aging on microstructural changes was investigated in stainless steel weld-overlay cladding composed of 90% austenite and 10% δ-ferrite phases using atom probe tomography (APT). In as-received materials subjected to cooling process after post-welding heat treatments (PWHT), a slight fluctuation of the Cr concentration was already observed due to spinodal decomposition in the ferrite phase but not in the austenitic phase. Thermal aging at 400 deg. C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the ferrite phase. The chemical compositions of M23C6 type carbides seemed to be formed at the austenite/ferrite interface were analyzed. The analyses of the magnitude of the spinodal decomposition and the hardness implied that the spinodal decomposition was the main cause of the hardening.

  5. Effect of SP-C on surface potential distribution in pulmonary surfactant: Atomic force microscopy and Kelvin probe force microscopy study

    International Nuclear Information System (INIS)

    The air-lung interface is covered by a molecular film of pulmonary surfactant (PS). The major function of the film is to reduce the surface tension of the lung's air-liquid interface, providing stability to the alveolar structure and reducing the work of breathing. Earlier we have shown that function of bovine lipid extract surfactant (BLES) is related to the specific molecular architecture of surfactant films. Defined molecular arrangement of the lipids and proteins of the surfactant film also give rise to a local highly variable electrical surface potential of the interface. In this work we investigated a simple model of artificial lung surfactant consisting of DPPC, eggPG, and surfactant protein C (SP-C). Effects of surface compression and the presence of SP-C on the monolayer structure and surface potential distribution were investigated using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We show that topography and locally variable surface potential of DPPC-eggPG lipid mixture are similar to those of pulmonary surfactant BLES in the presence of SP-C and differ in surface potential when SP-C is absent.

  6. Effect of SP-C on surface potential distribution in pulmonary surfactant: Atomic force microscopy and Kelvin probe force microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Hane, Francis [Department of Biology, Faculty of Science, University of Waterloo, Ontario (Canada); Moores, Brad [Department of Physics and Astronomy, Faculty of Science, University of Waterloo, Ontario (Canada); Amrein, Matthias [Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Alberta, Canada. (Canada); Leonenko, Zoya, E-mail: zleonenk@uwaterloo.ca [Department of Biology, Faculty of Science, University of Waterloo, Ontario (Canada); Department of Physics and Astronomy, Faculty of Science, University of Waterloo, Ontario (Canada)

    2009-07-15

    The air-lung interface is covered by a molecular film of pulmonary surfactant (PS). The major function of the film is to reduce the surface tension of the lung's air-liquid interface, providing stability to the alveolar structure and reducing the work of breathing. Earlier we have shown that function of bovine lipid extract surfactant (BLES) is related to the specific molecular architecture of surfactant films. Defined molecular arrangement of the lipids and proteins of the surfactant film also give rise to a local highly variable electrical surface potential of the interface. In this work we investigated a simple model of artificial lung surfactant consisting of DPPC, eggPG, and surfactant protein C (SP-C). Effects of surface compression and the presence of SP-C on the monolayer structure and surface potential distribution were investigated using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We show that topography and locally variable surface potential of DPPC-eggPG lipid mixture are similar to those of pulmonary surfactant BLES in the presence of SP-C and differ in surface potential when SP-C is absent.

  7. Effects of Laser Energy and Wavelength on the Analysis of LiFePO4 Using Laser Assisted Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Rich; Janssen, Yuri; Kalifah, Peter; Meng, Ying S.

    2015-01-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative accuracy of atom probe tomography (APT) examinations of LiFePO4 (LFP) are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted APT of LFP has revealed distinctly different behaviors. With the use of UV laser the major issue was identified as the preferential loss of oxygen (up to 10 at. %) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ increased the observed oxygen concentration to near its correct stoichiometry and was well correlated with systematically higher concentrations of 16O2+ ions. This observation supports the premise that lower laser energies lead to a higher probability of oxygen molecule ionization. Conversely, at higher laser energies the resultant lower effective electric field reduces the probability of oxygen molecule ionization. Green laser assisted field evaporation led to the selective loss of Li (~50% deficiency) and correct ratios of the remaining elements, including the oxygen concentration. The loss of Li is explained by selective dc evaporation of lithium between laser pulses and relatively negligible oxygen loss as neutrals during green-laser pulsing. Lastly, plotting of multihit events on a Saxey plot for the straight-flight path data (green laser only) revealed a surprising dynamic recombination process for some molecular ions mid-flight.

  8. Atom probe tomography study of Mg-dependent precipitation of Ω phase in initial aged Al-Cu–Mg–Ag alloys

    International Nuclear Information System (INIS)

    The association between Mg variations and the precipitation of Ω phase in Al–Cu–Mg–Ag alloys were investigated by transmission electron microscopy and quantitative atom probe tomography analysis. After aging at 165 °C for 2 h, the highest number density of Ω phase was revealed in 0.81Mg alloy, leading to the highest strength properties. The lowest strength properties of 0.39Mg alloy was related to the lowest precipitation kinetics of Ω phase. The parabolic change in the plate number density with increasing Mg highlighted the existence of a critical Mg content that contributed to the strongest precipitation kinetics of Ω phase. The number density of Mg–Ag co-clusters was not the sole factor in controlling the Ω precipitation. It was found that the precipitation of Ω phase was not only determined by initial Mg–Ag co-clustering but also related to the effective competition for solutes. In addition, the cluster-dominated microstructure facilitated the dense precipitation of Ω phase

  9. Analysis of dynamic segregation and crystallisation in Mg{sub 65}Cu{sub 25}Y{sub 10} bulk metallic glass using atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Laws, K.J., E-mail: k.laws@unsw.edu.au [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Saxey, D.W. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. (Australia); McKenzie, W.R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Electron Microscopy Unit, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW 2052 (Australia); Marceau, R.K.W. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Max-Planck Institut fuer Eisenforschung, Max-Planck-Str.1, Duesseldorf, D-40237 (Germany); Gun, B. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Ringer, S.P. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Ferry, M. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2012-10-30

    In order to develop an in-depth understanding of the flow behaviour and dynamic devitrification processes of metallic glasses in the supercooled liquid region, tensile testing of amorphous Mg{sub 65}Cu{sub 25}Y{sub 10} samples was carried out at temperatures from 150 to 170 Degree-Sign C and at strain rates from 1 Multiplication-Sign 10{sup -3} s{sup -1} to 1 Multiplication-Sign 10{sup -2} s{sup -1}. Tensile data showed a consistent and reproducible inflexion in flow stress at a particular strain that was largely independent of strain rate. This was followed by a dramatic increase in flow stress occuring prior to the determined onset times of static crystallisation. Samples were analysed using atom probe tomography and the results indicate that tensile straining of the initially homogeneous amorphous alloy results in segregation into two distinct glassy phases via a shear-related process, coincident with the maximum shear plane angle, followed by the evolution of regions corresponding to the composition of a number of equilibrium binary and ternary intermetallic phases.

  10. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Letellier, F.; Lardé, R.; Le Breton, J.-M., E-mail: jean-marie.lebreton@univ-rouen.fr [Groupe de Physique des Matériaux, UMR 6634 CNRS/Université et INSA de Rouen, F-76801 Saint Etienne du Rouvray (France); Lechevallier, L. [Groupe de Physique des Matériaux, UMR 6634 CNRS/Université et INSA de Rouen, F-76801 Saint Etienne du Rouvray (France); Département de GEII, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise (France); Akmaldinov, K. [SPINTEC, Univ. Grenoble-Alpes/CNRS/INAC-CEA, F-38000 Grenoble (France); CROCUS Technology, F-38025 Grenoble (France); Auffret, S.; Dieny, B.; Baltz, V., E-mail: vincent.baltz@cea.fr [SPINTEC, Univ. Grenoble-Alpes/CNRS/INAC-CEA, F-38000 Grenoble (France)

    2014-11-28

    Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.

  11. Atomic Force Microscopy, Scanning Kelvin Probe Force Microscopy and magnetic measurements on thermally oxidized AISI 304 and AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Research highlights: → The surface roughness of the bare substrate influence the oxide layer growth. → The oxide layer roughness follows power laws and belongs to universality class. → At low growth temperature, the p-n heterojunction disappears in some places. → SKPFM images allow the direct visualization of local corrosion sites. → Presence of a magnetite phase in the outer iron rich layer of the oxide thin film. - Abstract: Thermally oxidized AISI304 and AISI316 stainless steels are studied by Atomic Force Microscopy, Scanning Kelvin Probe Force Microscopy (SKPFM) and Magneto-Optical Kerr effect as a function of their growth temperature. The surface roughness is a competition between the roughness of the bare substrate and the roughness resulting from the oxide layer growth. Cr oxide is present at some places on the surface at low growth temperature as shown by SKPFM. The observed decrease of surface potential with the oxide layer thickness indicates an effective protection against corrosion. Magnetic measurements demonstrate that the outer layer contains a magnetite phase (in-plane magnetization).

  12. Use of biaxially oriented polypropylene film for evaluating and cleaning contaminated atomic force microscopy probe tips: An application to blind tip reconstruction

    Science.gov (United States)

    Nie, H.-Y.; Walzak, M. J.; McIntyre, N. S.

    2002-11-01

    An atomic force microscopy (AFM) image of a surface is basically a convolution of the probe tip geometry and the surface features; it is important to know this tip effect to ensure that an image truly reflects the surface features. We have found that a biaxially oriented polypropylene (BOPP) film is suitable for checking tip performance and for cleaning contaminated tips, thus making it possible to collect images of the same area of a BOPP film surface before and after the tip was cleaned. Therefore, the difference between the two different images is solely due to the contamination of the tip. We took advantage of our ability to collect AFM images of the same area using the same tip, in one instance, contaminated and, in the other, after being cleaned. First we used blind reconstruction on the image collected using the contaminated tip. Blind tip reconstruction allows one to extract the geometry of the tip from a given image. Once we had estimated the geometry of the contaminated tip, we used it to simulate the tip effect using the image collected using the cleaned tip. By comparing the simulation result with the image collected using the contaminated tip we showed that the blind reconstruction routine works well. Prior to this, there was no de facto method for testing blind reconstruction algorithms.

  13. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

    Science.gov (United States)

    Letellier, F.; Lechevallier, L.; Lardé, R.; Le Breton, J.-M.; Akmaldinov, K.; Auffret, S.; Dieny, B.; Baltz, V.

    2014-11-01

    Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.

  14. Laser-induced reversion of δ′ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    KAUST Repository

    Khushaim, Muna Saeed Amin

    2016-06-14

    The influence of tuning the laser pulse energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction, and composition of δ\\' precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser pulse energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser pulse energy of 100 pJ was in fairly good agreement with reported range of δ\\' solvus temperature, suggesting a result of reversion upon heating due to laser pulsing. © 2016 Wiley Periodicals, Inc.

  15. Preparation and characterization of optical-functional diblock copolymer brushes on hollow sphere surface via atom transfer radical polymerization

    International Nuclear Information System (INIS)

    The optical-functional poly(methyl methacrylate)-block-Tb complex diblock copolymer brushes grafted from hollow sphere surface via atom transfer radical polymerization were investigated in this work. A sufficient amount of azo initiator was introduced onto hollow sphere surface firstly. Then the monomer methyl methacrylate was polymerized via surface-initiated reverse atom transfer radical polymerization using azo group modified hollow sphere as initiator. Following, the poly(methyl methacrylate) modified hollow sphere was used as maroinitiator for surface-initiated atom transfer radical polymerization of Tb complex. The samples were characterized by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, gel permeation chromatographer and transmission electron microscopy, respectively. The results indicated that the poly(methyl methacrylate) had grafted from hollow sphere surface and the average diameter of hollow core was about 1 μm. The optical properties of the poly(methyl methacrylate)-block-Tb copolymer modified hollow sphere were also reported.

  16. Characterization of thermal inkjet technology TNT deposits by fiber optic-grazing angle probe FTIR spectroscopy

    Science.gov (United States)

    Primera-Pedrozo, Oliva M.; Pacheco-Londono, Leonardo; Ruiz, Orlando; Ramirez, Michael; Soto-Feliciano, Yadira M.; De La Torre-Quintana, Luis F.; Hernandez-Rivera, Samuel P.

    2005-05-01

    Fiber Optic Coupled/Grazing Angle Probe Fourier Transform Infrared Spectroscopy has made possible to develop new methods for detection of traces of chemical compounds on surfaces. Thermal Inkjet Technology is able to deposit very small amounts of chemical compounds, including energetic materials, in a specific location on a surface. Aliquots of TNT solutions were deposited on stainless steel film. A thin coating of TNT can be produced by controlling the concentration of TNT, the number of drops dispensed and the distribution of drops over the surface. A Vector 22, a Bruker Optics FTIR fiber coupled to a Remspec Corp. grazing angle head was used for the experiments. The spectra were recorded at 4 cm-1 resolution and 50 scans. The results of the experiments gave intense absorption bands in the fingerprint region of the infrared spectra that were used for quantification. Chemometrics routines were applied in the enhancement of the quantitative analysis.

  17. Fabrication, characterization, and functionalization of dual carbon electrodes as probes for scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    McKelvey, Kim; Nadappuram, Binoy Paulose; Actis, Paolo; Takahashi, Yasufumi; Korchev, Yuri E; Matsue, Tomokazu; Robinson, Colin; Unwin, Patrick R

    2013-08-01

    Dual carbon electrodes (DCEs) are quickly, easily, and cheaply fabricated by depositing pyrolytic carbon into a quartz theta nanopipet. The size of DCEs can be controlled by adjusting the pulling parameters used to make the nanopipet. When operated in generation/collection (G/C) mode, the small separation between the electrodes leads to reasonable collection efficiencies of ca. 30%. A three-dimensional finite element method (FEM) simulation is developed to predict the current response of these electrodes as a means of estimating the probe geometry. Voltammetric measurements at individual electrodes combined with generation/collection measurements provide a reasonable guide to the electrode size. DCEs are employed in a scanning electrochemical microscopy (SECM) configuration, and their use for both approach curves and imaging is considered. G/C approach curve measurements are shown to be particularly sensitive to the nature of the substrate, with insulating surfaces leading to enhanced collection efficiencies, whereas conducting surfaces lead to a decrease of collection efficiency. As a proof-of-concept, DCEs are further used to locally generate an artificial electron acceptor and to follow the flux of this species and its reduced form during photosynthesis at isolated thylakoid membranes. In addition, 2-dimensional images of a single thylakoid membrane are reported and analyzed to demonstrate the high sensitivity of G/C measurements to localized surface processes. It is finally shown that individual nanometer-size electrodes can be functionalized through the selective deposition of platinum on one of the two electrodes in a DCE while leaving the other one unmodified. This provides an indication of the future versatility of this type of probe for nanoscale measurements and imaging.

  18. Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing.

    Science.gov (United States)

    Ling, Xue; Wang, Yusheng; Li, Xide

    2014-10-01

    An electromechanically-coupled micro-contact resistance measurement system is built to mimic the contact process during fatigue testing of nanoscale-thickness interconnects using multiple probe methods. The design combines an optical microscope, high-resolution electronic balance, and micromanipulator-controlled electric probe, and is coupled with electrical measurements to investigate microscale contact physics. Experimental measurements are performed to characterize the contact resistance response of the gold nanocrystalline pad of a 35-nm-thick interconnect under mechanical force applied by a tungsten electrode probe. Location of a stable region for the contact resistance and the critical contact force provides better understanding of micro-contact behavior relative to the effects of the contact force and the nature of the contact surface. Increasing contact temperature leads to reduced contact resistance, softens the pad material, and modifies the contact surface. The stability of both contact resistance and interconnect resistance is studied under increasing contact force. Major fluctuations emerge when the contact force is less than the critical contact force, which shows that temporal contact resistance will affect interconnect resistance measurement accuracy, even when using the four-wire method. This performance is demonstrated experimentally by heating the Au line locally with a laser beam. Finally, the contact resistances are calculated using the LET (Li-Etsion-Talke) model together with combined Holm and Sharvin theory under various contact forces. Good agreement between the results is obtained. This research provides a way to measure change in interconnect line resistance directly under a stable contact resistance regime with a two-wire method that will greatly reduce the experimental costs. PMID:25362435

  19. Crystallization, phase evolution and corrosion of Fe-based metallic glasses: An atomic-scale structural and chemical characterization study

    International Nuclear Information System (INIS)

    Understanding phase changes, including their formation and evolution, is critical for the performance of functional as well as structural materials. We analyze in detail microstructural and chemical transformations of the amorphous steel Fe50Cr15Mo14C15B6 during isothermal treatments at temperatures ranging from 550 to 800 °C. By combining high-resolution transmission electron microscopy and Rietveld analyses of X-ray diffraction patterns together with the local chemical data obtained by atom probe tomography, this research provides relevant information at the atomic scale about the mechanisms of crystallization and the subsequent phases evolution. During the initial stages of crystallization a stable (Fe,Cr)23(C,B)6 precipitates as well as two metastable intermediates of M3(C,B) and the intermetallic χ-phase. When full crystallization is reached, only a percolated nano-scale Cr-rich (Fe,Cr)23(C,B)6 and Mo-rich η-Fe3Mo3C structure is detected, with no evidence to suggest that other phases appear at any subsequent time. Finally, the corrosion behavior of the developed phases is discussed from considerations of the obtained atomic information

  20. Characterization of graphene and transition metal dichalcogenide at the atomic scale

    International Nuclear Information System (INIS)

    Edge structures and atomic defects are of fundamental importance since they can significantly affect the physical and chemical properties of low-dimensional materials, such as nanoribbons, and therefore merit thorough investigations at the atomic level. Recent developments of direct imaging and analytical techniques using an aberration-corrected scanning transmission electron microscope (STEM) have provided direct access to information on the local atomic structure and the chemical composition at the atomic scale. In this review, we report on the discrimination of single atoms including dopant atoms on a monolayered transition-metal dichalcogenide (TMD) nanoribbon and a single nitrogen adatom on graphene by time-resolved annular dark-field (ADF) imaging and spatially resolved electron energy loss spectroscopy (EELS). We also show that in situ scanning transmission electron microscopy can be used to monitor the structural transformation between semiconducting (2H) and metallic (1T) phases in monolayer MoS2, and can enable direct observation of in-plane graphene growth at a step edge of a bi-layer graphene and domain boundary formation during growth with atomic-resolution. (author)

  1. Characterization of Graphene and Transition Metal Dichalcogenide at the Atomic Scale

    Science.gov (United States)

    Liu, Zheng; Lin, Yung-Chang; Warner, Jamie H.; Teng, Po-Yuan; Yeh, Chao-Hui; Chiu, Po-Wen; Iijima, Sumio; Suenga, Kazu

    2015-12-01

    Edge structures and atomic defects are of fundamental importance since they can significantly affect the physical and chemical properties of low-dimensional materials, such as nanoribbons, and therefore merit thorough investigations at the atomic level. Recent developments of direct imaging and analytical techniques using an aberration-corrected scanning transmission electron microscope (STEM) have provided direct access to information on the local atomic structure and the chemical composition at the atomic scale. In this review, we report on the discrimination of single atoms including dopant atoms on a monolayered transition-metal dichalcogenide (TMD) nanoribbon and a single nitrogen adatom on graphene by time-resolved annular dark-field (ADF) imaging and spatially resolved electron energy loss spectroscopy (EELS). We also show that in situ scanning transmission electron microscopy can be used to monitor the structural transformation between semiconducting (2H) and metallic (1T) phases in monolayer MoS2, and can enable direct observation of in-plane graphene growth at a step edge of a bi-layer graphene and domain boundary formation during growth with atomic-resolution.

  2. Characterization of Fe2+ Ions in Fe,H/SSZ-13 Zeolites: FTIR Spectroscopy of CO and NO Probe Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Szanyi, Janos; Gao, Feng; Kwak, Ja Hun; Kollar, Marton; Wang, Yilin; Peden, Charles HF

    2016-04-11

    The IR spectra of adsorbed CO and NO probe molecules were used to characterize the coordination chemistry of Fe2+ ions in solution ion exchanged Fe,H/SSZ-13 zeolites. The effects of Fe ion exchange levels, as well the sample pre-treatment conditions on the adsorption of these probe molecules were investigated. The ion exchange levels (in the range of the study) did not affect significantly the IR spectra of either probe molecule, the IR features and their intensity ratios were very similar. Experiments with both probe molecules substantiated the presence of two distinct types of Fe2+ ions in cationic positions. We assign these two Fe2+ ions to two distinct cationic positions: Fe2+ in 6R and 8R positions. NO initially adsorbs preferentially onto Fe2+ sites in the 6R position, and then populates sites in the 8R. Fe2+ ions in the 8R positions require the interaction of more than one NO molecule to move them out from their adsorbate-free cationic positions. As soon as they move from their stable positions, they are able to bind to multiple NO molecules, and form mostly tri-nitrosyls. These tri-nitrosyls, however, are only stable in the presence of gas phase NO; under dynamic vacuum they lose one of the NO molecules from their coordination sphere and form stable di-nitrosyls. The adsorption of CO is much weaker on Fe2+ sites than that of NO, and requires cryogenic sample temperatures to initiate CO adsorption. Under the conditions applied in this study, only mono-carbonyl formation was observed. Reduction in H2 at 773 K increased the number of Fe2+ adsorption sites, primarily in the 8R locations. Oxidation by N2O, on the other hand, selectively reduced the adsorption of both CO and NO on the Fe2+ sites in 8R positions. Adsorbed oxygen left behind from the decomposition of N2O at 573 K readily reacted with CO to produce CO2 even at 150 K. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies

  3. Characterization of gold nanoparticle films: Rutherford backscattering spectroscopy, scanning electron microscopy with image analysis, and atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Pia C. Lansåker

    2014-10-01

    Full Text Available Gold nanoparticle films are of interest in several branches of science and technology, and accurate sample characterization is needed but technically demanding. We prepared such films by DC magnetron sputtering and recorded their mass thickness by Rutherford backscattering spectroscopy. The geometric thickness dg—from the substrate to the tops of the nanoparticles—was obtained by scanning electron microscopy (SEM combined with image analysis as well as by atomic force microscopy (AFM. The various techniques yielded an internally consistent characterization of the films. In particular, very similar results for dg were obtained by SEM with image analysis and by AFM.

  4. Probing Capacity

    CERN Document Server

    Asnani, Himanshu; Weissman, Tsachy

    2010-01-01

    We consider the problem of optimal probing of states of a channel by transmitter and receiver for maximizing rate of reliable communication. The channel is discrete memoryless (DMC) with i.i.d. states. The encoder takes probing actions dependent on the message. It then uses the state information obtained from probing causally or non-causally to generate channel input symbols. The decoder may also take channel probing actions as a function of the observed channel output and use the channel state information thus acquired, along with the channel output, to estimate the message. We refer to the maximum achievable rate for reliable communication for such systems as the 'Probing Capacity'. We characterize this capacity when the encoder and decoder actions are cost constrained. To motivate the problem, we begin by characterizing the trade-off between the capacity and fraction of channel states the encoder is allowed to observe, while the decoder is aware of channel states. In this setting of 'to observe or not to o...

  5. Electrochemical and scanning probe microscopic characterization of spontaneously adsorbed organothiolate monolayers at gold

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Sze-Shun Season

    1999-12-10

    This dissertation presented several results which add to the general knowledge base regarding organothiolates monolayer spontaneously adsorbed at gold films. Common to the body of this work is the use of voltammetric reductive resorption and variants of scanning probe microscopy to gain insight into the nature of the monolayer formation process as well as the resulting interface. The most significant result from this work is the success of using friction force microscopy to discriminate the end group orientation of monolayer chemisorbed at smooth gold surfaces with micrometer resolution (Chapter 4). The ability to detect the differences in the orientational disposition is demonstrated by the use PDMS polymer stamp to microcontact print an adlayer of n-alkanethiolate of length n in a predefine pattern onto a gold surface, followed by the solution deposition of a n-alkanethiol of n {+-} 1 to fill in the areas on the gold surface intentionally not coated by the stamping process. These two-component monolayers can be discriminated by using friction force microscopy which detects differences in friction contributed by the differences in the orientation of the terminal groups at surfaces. This success has recently led to the detection of the orientation differences at nanometer scale. Although the substrates examined in this work consisted entirely of smooth gold films, the same test can be performed on other smooth substrates and monolayer materials.

  6. Gas sensing characterization of tellurium thin films by the Kelvin probe technique

    International Nuclear Information System (INIS)

    The sensing behavior of tellurium films at room temperature was tested with environmental pollutant gases, such as NO2, CO, O3, and water vapor, using the Kelvin probe technique. A significant sensitivity was observed for nitrogen dioxide. The detection range for NO2 was between 0.5-5.0 ppm in air with controlled humidity. The response and the recovery time are rapid with good reproducibility and high sensibility. The work function measurements showed that chalcogenide semiconductors in question are well-suited materials for the detection of not only small concentrations of NO2, but also for humidity sensing. The relative humidity of 45% induces the work function change Δ φ of approximately 200 mV at room temperature. It is shown that the 'strong' chemisorption of nitrogen dioxide results in an increase in both work function change Δ Φ > 0 and electrical conductivity Δ c > 0 because of the additional charging of the surface and band bending. The effect of water vapor is due to a simple physical adsorption of polar water molecules oriented perpendicular to the surface with a negative pole inward. As a result, the dipole component of the work function increases, i.e., Δ Φ > 0, but the free lattice holes become more localized at the surface and the conductivity of the p-type chalcogenide layer decreases Δ c < 0. (authors)

  7. A piezo-thermal probe for thermomechanical analysis

    NARCIS (Netherlands)

    Gaitas, A.; Gianchandani, S.; Zhu, W.

    2011-01-01

    Thermomechanical analysis (TMA) is widely used to characterize materials and determine transition temperatures and thermal expansion coefficients. Atomic-force microscopy (AFM) microcantilevers have been used for TMA. We have developed a micromachined probe that includes two embedded sensors: one fo

  8. Formation and characterization of thin films from phthalocyanine complexes: An electrosynthesis study using the atomic-force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Vergara, M.E. [Departamento de Ingenieria Mecatronica, Escuela de Ingenieria, Universidad Anahuac del Norte, Avenida Lomas de la Anahuac s/n, Col. Lomas Anahuac, 52786, Huixquilucan (Mexico)]. E-mail: elena.sanchez@anahuac.mx; Islas Bernal, I.F. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510, Mexico D.F. (Mexico); Rivera, M. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510, Mexico D.F. (Mexico); Ortiz Rebollo, A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan, 04510, Mexico, D.F. (Mexico); Alvarez Bada, J.R. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222, Col. Ejidos de Huipulco, 14380, Mexico D.F. (Mexico)

    2007-05-07

    ({mu}-Cyano)(phthalocyaninato)metal(III) [PcMCN]{sub n} species with a central transition metal ion, such as Fe(III) and Co(III), were used to prepare molecular films on a highly oriented pyrolytic graphite electrode substrate by using the cyclic voltammetry technique. In order to investigate the influence of the ligand on the film properties, 1,8-dihydroxyanthraquinone and 2,6-dihydroxyanthraquinone as bivalent ligands were employed. The structure of the molecular materials was analyzed by infrared spectroscopy. The in situ film formation, texture, composition and conductivity of each film were further investigated using atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and the four-probe technique, respectively. The [PcMCN]{sub n} complexes provided conductive films with an electrical conductivity of 1 x 10{sup -6} {omega}{sup -1} cm{sup -1} at 298 K.

  9. Formation and characterization of thin films from phthalocyanine complexes: An electrosynthesis study using the atomic-force microscope

    International Nuclear Information System (INIS)

    (μ-Cyano)(phthalocyaninato)metal(III) [PcMCN]n species with a central transition metal ion, such as Fe(III) and Co(III), were used to prepare molecular films on a highly oriented pyrolytic graphite electrode substrate by using the cyclic voltammetry technique. In order to investigate the influence of the ligand on the film properties, 1,8-dihydroxyanthraquinone and 2,6-dihydroxyanthraquinone as bivalent ligands were employed. The structure of the molecular materials was analyzed by infrared spectroscopy. The in situ film formation, texture, composition and conductivity of each film were further investigated using atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and the four-probe technique, respectively. The [PcMCN]n complexes provided conductive films with an electrical conductivity of 1 x 10-6 Ω-1 cm-1 at 298 K

  10. Effects of laser energy and wavelength on the analysis of LiFePO4 using laser assisted atom probe tomography

    International Nuclear Information System (INIS)

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO4 by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygen concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of 16O2+ ions. Green laser assisted field evaporation led to the selective loss of Li (∼33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO4. Plotting of multihit events on Saxey plots also revealed a strong neutral O2 loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency. - Highlights: • Laser wavelength and pulse energy affect accuracy of APT analysis of LiFePO4. • Oxygen deficiency observed for UV laser; stronger at higher laser energies. • Selective loss of Li with green laser due to dc evaporation. • Saxey plots reveal prevalent formation of O2 neutrals. • Quantification of molecular dissociations cannot account for O deficiency

  11. Role of W and Mn for reliable 1X nanometer-node ultra-large-scale integration Cu interconnects proved by atom probe tomography

    International Nuclear Information System (INIS)

    We used atom probe tomography (APT) to study the use of a Cu(Mn) as a seed layer of Cu, and a Co(W) single-layer as reliable Cu diffusion barriers for future interconnects in ultra-large-scale integration. The use of Co(W) layer enhances adhesion of Cu to prevent electromigration and stress-induced voiding failures. The use of Cu(Mn) as seed layer may enhance the diffusion barrier performance of Co(W) by stuffing the Cu diffusion pass with Mn. APT was used to visualize the distribution of W and Mn in three dimensions with sub-nanometer resolution. W was found to segregate at the grain boundaries of Co, which prevents diffusion of Cu via the grain boundaries. Mn was found to diffuse from the Cu(Mn) layer to Co(W) layer and selectively segregate at the Co(W) grain boundaries with W, reinforcing the barrier properties of Co(W) layer. Hence, a Co(W) barrier coupled with a Cu(Mn) seed layer can form a sufficient diffusion barrier with film that is less than 2.0-nm-thick. The diffusion barrier behavior was preserved following a 1-h annealing at 400 °C. The underlayer of the Cu interconnects requires a large adhesion strength with the Cu, as well as low electrical resistivity. The use of Co(W) has previously been shown to satisfy these requirements, and addition of Mn is not expected to deteriorate these properties.

  12. Physical characterization of the state of motion of the phenalenyl spin probe in cation-exchanged faujasite zeolite supercages with pulsed EPR

    Science.gov (United States)

    Doetschman, D. C.; Dwyer, D. W.; Fox, J. D.; Frederick, C. K.; Scull, S.; Thomas, G. D.; Utterback, S. G.; Wei, J.

    1994-08-01

    The molecular motion of the phenalenyl (PNL) spin probe in the supercages of cation-exchanged X and Y zeolites (faujasites) has been physically characterized by pulsed and continuous wave (CW) electron paramagnetic resonance (EPR). Both X and Y zeolites, whose cation sites were exchanged with the alkali metal ions, Li +, Na +, K +, Rb + and Cs + were examined. There is a good correspondence between the temperature dependences of the PNL electron spin phase memory time and the CW EPR spectra. Both display evidence of a thermal activation from a stationary, non-rotating molecular state to a low-temperature state of in-plane rotation (Das et al., Chem Phys. 143 (1990) 253). The rate of in-plane rotation is an activated process, with E* | / R=1289 |+- 35 K and 1462 ± 47 K in NaX and KX zeolites, respectively. The rotation appears to be about an axis along which the half-filled, non-bonding π orbital interacts with the exchanged cation in the supercage. Both CW and pulsed EPR also show a higher temperature activation from the in-plane rotating state to an effectively isoptropic state of rotation of PNL in which the PNL-cation bond is thought to be broken, with E* ⊥ / R=2050 ± 110 K, 1956 ± 46K, 1335 ± 97 K in LiX, NaX and KX zeolites, respectively. The strength of the PNL-cation bonding decreases with increasing cation atomic number as indicated by E* ⊥ and the peripheral repulsion (crowding) of PNL increases with cation size as indicated E* |. There are qualitative indications that the binding of PNL to the cations in the Y zeolite is stronger than in the X zeolite.

  13. Application of scanning Kelvin probe microscopy for the electrical characterization of microcrystalline silicon for photovoltaics

    CERN Document Server

    Breymesser, A

    2000-01-01

    constructed and built. Great effort was concentrated on the characterization of the SKPM experiment. On the basis of an extended knowledge about the performance investigations concentrated on cross sections of microcrystalline silicon diode structures produced by hot-wire chemical vapor deposition (HW-CVD). A pin structure for the diodes was chosen due to the low diffusion lengths within this rather defective material. The evolution of the built-in electric drift field within the intrinsic absorber is a prerequisite for obtaining high short circuit current densities. SKPM was able to provide information about the potential and electric field distribution within the cross-sectioned diode structures. In conjunction with simulations statements about actual defect and dopant distributions could be derived. Several diode structures with different deposition and compensation conditions of the naturally n-type intrinsic layer were investigated. In order to explore the character of the defects deep level transient sp...

  14. Electronic characterization of supramolecular materials at the nanoscale by Conductive Atomic Force and Kelvin Probe Force microscopies

    Directory of Open Access Journals (Sweden)

    Chiara Musumeci

    2014-12-01

    Full Text Available The performances of organic (optoelectronic devices strongly depend on the order at the supramolecular level. Unraveling the relationship between structural and electronic properties in nanoscale architectures is therefore key for both fundamental studies and technological applications. C-AFM and KPFM provide an immediate correlation between the morphology of a material and its electrical/electronic properties such as local conductivity and surface potential. Thus, they are unrivaled techniques offering crucial information toward the optimization of the real devices, ultimately providing an important contribution to a hot field at the cross-road between nanoscience and organic (optoelectronics. Herein we focus on the application of C-AFM and KPFM on self-assembled monolayers (SAMs, organic (semiconducting materials for thin film transistors (TFTs and organic blends for photovoltaics (OSCs.

  15. Characterization of Al2O3 Thin Films on GaAs Substrate Grown by Atomic Layer Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Hong-Liang; LI Yan-Bo; XU Min; DING Shi-Jin; SUN Liang; ZHANG Wei; WANG Li-Kang

    2006-01-01

    @@ Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction (XRD), highresolution transmission electron microscopy (HRTEM), and x-ray photoelectron spectroscopy (XPS). The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3nm and 0.5nm, respectively.XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.

  16. Characterization of novel sufraces by FTIR spectroscopy and atomic force microscopy for food pathogen detection

    Science.gov (United States)

    Single molecular detection of pathogens and toxins of interest to food safety is within grasp using technology such as Atomic Force Microscopy. Using antibodies or specific aptamers connected to the AFM tip make it possible to detect a pathogen molecule on a surface. However, it also becomes necess...

  17. Characterization and modeling of atomic layer deposited high-density trench capacitors in silicon

    NARCIS (Netherlands)

    Matters-Kammerer, M.K.; Jinesh, K.B.; Rijks, T.G.S.M.; Roozeboom, F.; Klootwijk, J.H.

    2012-01-01

    A detailed electrical analysis of multiple layer trench capacitors fabricated in silicon with atomic-layer-deposited Al 2O 3 and TiN is presented. It is shown that in situ ozone annealing of the Al 2O 3 layers prior to the TiN electrode deposition significantly improves the electric properties of th

  18. In-situ RHEED analysis of atomic layer deposition and characterization of AL203 gate dielectrics

    NARCIS (Netherlands)

    Bankras, R.G.; Aarnink, A.A.I.; Holleman, J.; Schmitz, J.

    2003-01-01

    A new custom designed reactor was realized at the MESA+ cleanroom to fabricate high-k dielectrics using atomic layer deposition (ALD). Key features of the reactor are: a small reactor volume, in-situ RHEED analysis and low background pressure. The effect of precursor and purge pulse times is discuss

  19. Characterization of Atmospheric Aerosol Particles from a Mining City in Southwest China Using Electron Probe microanalysis

    Science.gov (United States)

    Cheng, X.; Huang, Y.; Lu, H., III; Liu, Z., IV; Wang, N. V.

    2015-12-01

    Xin Cheng1, Yi Huang1*, Huilin Lu2, Zaidong Liu2, Ningming Wang21 Key Laboratory of Geological Nuclear Technology of Sichuan Province, College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; E-mail:chengxin_cdut@163.com 2 College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; *Corresponding author: E-mail: huangyi@cdut.cn Panzhihua is a mining city located at Pan-Xi Rift valley, southwest China. It has a long industrial history of vanadium-titanium magnetite mining, iron and steel smelting, and coal-fired power plants. Atomospheric environment has been seriously contaminated with airborne paticles, which is threatening human health.The harmful effects of aerosols are dependent on certain characteristics such as microphysical properties. However, few studsies have been carried out on morphological information contained on single atmospheric particles in this area. In this study, we provide a detailed morphologically and chemically characterization of airborne particles collected at Panzhihua city in October, 2014, using a quantitative single particle analysis based on EPXMA. The results indicate that based on their chemical composition, five major types of particles were identified. Among these, aluminosilicate particles have typical spherical shapes and are produced during the high-temperature combustion; Fe-containing particles contains high level of Mn, and more likely originated from mineralogical and steel industry; Si-containing particles can originate from mineralogical source; V-Ti-Mn-containing particles are also produced by steel industry; Ca-containing particles,these particles are CaCO3, mainly from the mining of limestone mine. The results help us on tracing and partitioning different sources of atomospheric particles in the industrial area. Fig.1 Fe-rich shperical particles

  20. 2H-NMR CHARACTERIZATION OF CLAY DISPERSION AND CONFINEMENT EFFECT ON PROBE MOLECULES IN RUBBER/CLAY NANOCOMPOSITE-GELS

    Institute of Scientific and Technical Information of China (English)

    Ping-chuan Sun; Jian-jun Zhu; Tie-hong Chen

    2009-01-01

    2H-NMR spectroscopy of the probe molecule,deuterated benzene,was applied to characterize organo-clay dispersion and confinement effect on the local motion of benzene in rubber/clay nanocomposite-gels.The observed 2H line shapes of benzene in intercalated and exfoliated nanocomposites were obviously different,which can be used to estimate clay-dispersion quality.2H-NMR line shapes also reflect the different influence of intercalated or exfoliated layered-silicates on local motions of benzene,implying that probe molecules exhibit different local motions depending on different confined geometry in these nanocomposites.Viscosity measurements further confirmed these NMR results.